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Bible Encyclopedias
Cetacea
1911 Encyclopedia Britannica
or (from the Gr. Ktos, a whale), the name of the mammalian order represented by whales, dolphins, porpoises, &c. From their fish-like form, which is manifestly merely an adaptation to their purely aquatic life, these creatures are often regarded as fishes, although they are true mammals, with warm blood, and suckle their young.
The general form is essentially fish-like, the spindle-shaped body passing anteriorly into the head without any distinct neck, and posteriorly tapering gradually towards the extremity of the tail, which is provided with a pair of lateral, pointed expansions of skin supported by fibrous tissue, called "flukes," forming a horizontal triangular propelling organ, notched behind in the middle line. The head is generally large, in some cases attaining more than one-third the entire length; and the mouth is wide, and bounded by stiff, immobile lips. The fore-limbs are reduced to flattened paddles, encased in a continuous skin, showing no external sign of division, and without trace of nails. There are no signs of hind-limbs visible externally. The surface of the skin is smooth and glistening, and devoid of hair, although in many species there are a few bristles in the neighbourhood of the mouth which may persist through life or be present only in the young state. Immediately beneath the skin is a thick layer of fat, held together by a mesh of tissue, constituting the "blubber," which retains the heat of the body. In nearly all species a compressed dorsal fin is present. The eye is small, and not provided with a true lacrymal apparatus. The external ear is a minute aperture in the skin situated at a short distance behind the eye. The nostrils open separately or by a single crescentic aperture, near the vertex of the head.
number in mammals, sometimes considerably; they present the exceptional character of having epiphyses at both ends. The pelvis is represented by a pair of small rod-like bones placed longitudinally, suspended below and at some distance from the vertebral column at the commencement of the tail. In some species, to the outer surface of these are fixed other small bones or cartilages, the rudiments of the hind-limb.
Teeth are generally present, but exceedingly variable in number. In existing species, they are of simple, uniform character, with conical or compressed crowns and single roots, and are never preceded by milk-teeth. In the whalebone whales teeth are absent (except in the foetal condition), and the palate is provided with numerous transversely placed horny plates, forming the "whalebone." Salivary glands are rudimentary or absent. The stomach is complex, and the intestine simple, and only in some species provided with a small caecum. The liver is little fissured, and there is no gall-bladder. The blood-vascular system is complicated by net-like expansions of both arteries and veins, or reties n21rabilia. The larynx is of peculiar shape, the arytenoid cartilages and the epiglottis being elongated, and forming a tubular prolongation, IG. 1. - A Section of the Skull of a Black-Fish (Globicephalus melas) x AS, Alisphenoid.
PS, Presphenoid.
the mes- Pt, Pterygoid.
pn, Posterior pares.
Pl, Palatine.
Vo, Vomer.
s, Symphysis of lower jaw.
id, Inferior dental canal.
cp, Coronoid process of lower jaw. cd, Condyle.
a, Angle.
sh, Stylo-hyal.
bh, Basi-hyal.
th, Thyro-hyal.
which projects into the posterior nares, and when embraced by the soft palate forms a continuous passage between the nostrils and the trachea, or wind-pipe, in a more perfect manner. The brain is relatively large, round in form, with its surface divided into numerous and complex convolutions. The kidneys are deeply lobulated; the testes are abdominal; and there are no vesiculae seminales nor an os penis. The uterus is bicornuate; the placenta non-deciduate and diffuse. The two teats are placed in depressions on each side of the genital aperture. The ducts of the milk-glands are dilated during suckling into large reservoirs, into which the milk collects, and from which it is injected by the action of a muscle into the mouth of the young animal, so that sucking under water is greatly facilitated.
Whales and porpoises are found in all seas, and some dolphins and porpoises are inhabitants of the larger rivers of South America and Asia. Their organization necessitates their passing their life entirely in the water, as on land they are absolutely helpless. They have, however, to rise very frequently to the surface for the purpose of respiration; and, in relation to the upward and downward movement in the water thus necessitated, the principal instrument of motion, the tail, is expanded horizontally. The position of the nostril on the highest part of the head is important for this mode of life, as it is the only part of the body the exposure v. 2 5 The bones generally are spongy in texture, the cavities being filled with oil. In the vertebral column, the cervical region is short and immobile, and the vertebrae, always seven in number, are in many species more or less fused together into a solid mass. The odontoid process of the second cervical vertebra, when that bone is free, is usually very obtuse, or even obsolete. In a paper on the form and function of the cervical vertebrae published in the Jenaische Zeitschrift for 1905, Dr O. Reche points out that the shortening and soldering is most pronounced in species which, like the right-whales, live entirely on minute organisms, to capture which there is no necessity to turn the head at all. Accordingly we find that in these whales the whole seven cervical vertebrae are fused into an immovable solid mass, of which the compound elements, with the exception of the first and second, are but little thicker than plates. On the other hand, in the fanner-whales, several of which live exclusively on fish, and thus require a certain amount of mobility in the head and neck, we find all the cervical vertebrae much thicker and entirely separate from one another. F Among the dolphin group the narwhal and the white whale, or P beluga, are distinguished from all other cetaceans by the great corn parative length of their cervical vertebrae, all of which are completely free. In the case of the narwhal such an abnormal structure is easily accounted for, seeing that to use effectively the long tusk a with which the male is armed a considerable amount of mobility in the neck is absolutely essential. The beluga, too, which is believed to feed on large and active fishes, would likewise seem to require mobility in the same region in order to effect their capture. On P the other hand, the porpoise preys on herrings, pilchards and s mackerel, which in their densely packed shoals must apparently E fall an easy prey with but little exertion on the part of their B captor, and we accordingly find all the neck-vertebrae very short, s and at least six out of the seven coalesced into a solid immovable mass. None of the vertebrae are united to form a sacrum. The lumbar and caudal vertebrae are numerous and large, and, as their arches are not connected by articular processes (zygapophyses), they are capable of free motion in all directions. The caps, or epiphyses, at the end of the vertebral bodies are flattened disks, not uniting until after the animal has attained its full dimensions. There are largely developed chevron-bones on the under side of the tail, the presence of which indicates the distinction between caudal and lumbar vertebrae.
In the skull, the brain-case is short, broad and high, almost spherical, in fact (fig. I). The supra-occipital bone rises upwards and forwards from the foramen magnum, to meet the frontals at the vertex, completely excluding the parietals from the upper region; and the frontals are expanded laterally to form the roof of the orbits. The nasal aperture opens upwards, and has in front of it a more or less horizontally prolonged beak, formed of the maxillae, premaxillae, vomer, and mesethmoid cartilage, extending forwards to form the upper jaw or roof of the mouth.
There are no clavicles. The humerus is freely movable on the scapula at the shoulder-joint, but beyond this the articulations of the limb are imperfect; the flattened ends of the bones coming in contact, with fibrous tissue interposed, allowing of scarcely any motion. The radius and ulna are distinct, and about equally developed, and much flattened, as are all the bones of the flippers. There are four, or more commonly five, digits, and the number of the phalanges of the second and third always exceeds the normal Mx, Premaxilla.
Mx, Maxilla.
ME, Ossified portion of ethmoid.
(I n, Nostrils. v Nasal. I P, Inter-parietal.
Fr, Frontal. a, Parietal.
0, Supra-occipital. x0, Ex-occipital.
0, Basi-occipital.
q, Squamosal. er, P eriotic.
of which above the surface is absolutely necessary. Of numerous erroneous ideas connected with natural history, few are so widespread as that whales spout through their blow-holes water taken in at the mouth. But the "spouting," or "blowing," of whales is nothing more than the ordinary act of expiration, which, taking place at longer intervals than land-animals, is performed with a greater emphasis. The moment the animal rises to the surface it forcibly expels from its lungs the air taken in at the last inspiration, which is charged with vapour in consequence of the respiratory changes. This rapidly condensing in the cold atmosphere in which the phenomenon is often observed, forms a column of steam or spray, which has been taken for water. It happens, however, especially when the surface of the ocean is agitated into waves, that the animal commences its expiratory puff before the orifice has cleared the top of the water, some of which may thus be driven upwards with the blast, tending to complete the illusion. From photographs of spouting rorquals, it appears that the height and volume of the "spout" of all the species is much less than was supposed to be the case by the older observers; even that of the huge "sulphur-bottom" (Balaenoptera sibbaldi) averaging only about 14 ft. in: height, although it may occasionally reach 20 ft.
As regards their powers of hearing, the capacity of cetaceans for receiving (and acting upon) sound-waves is demonstrated by the practice of shouting on the part of the fishermen when engaged in driving a shoal of porpoises or black-fish into shallow water, for the purpose of frightening their intended victims. As regards the possession of a voice by cetaceans, it is stated that one species, the "buckelwal" of the Germans, utters during the breedingseason a prolonged scream, comparable to the scream of a steamsiren, and embracing the whole musical scale, from base to treble. In respect of anatomical considerations, it is true that the external ear is much reduced, the "pinna" being absent, and the tube or "meatus" of very small calibre. On the other hand, the internal auditory organs are developed on the plan of those of ordinary mammals, but display certain peculiar modifications (notably the remarkable shell-like form of the tympanic bone) for intensifying and strengthening the sound-waves as they are received from the water. It seems, therefore, perfectly evident that whales must hear when in the water. This inference is confirmed by the comparatively small development of the other sense-organs. The eye, for instance, is very small, and can be of little use even at the comparatively small depths to which whales are now believed to descend. Again, the sense of smell, judging from the rudimentary condition of the olfactory organs, must be in abeyance; and whales have no sense-organs comparable to the lateral-line-system of fishes. Consequently, it would seem that when below the surface of the water they must depend chiefly upon the sense of hearing. Probably this sense is so highly developed as to enable the animals, in the midst of the vibrations made by the screw-like movements of the tail, or flukes, to distinguish the sound (or the vibrations) made by the impact of water against rocks, even in a dead calm, and, in the case of piscivorous species, to recognize by the pulse in the water the presence of a shoal of fish. Failing this explanation, it is difficult to imagine how whales can find their way about in the semi-darkness, and avoid collisions with rocks and rock-bound coasts.
In the Christiania Nyt Magazin for Naturvidenskaberne, vol. xxxviii., Dr G. Guldberg has published some observations on the body-temperature of the Cetacea, in which he shows how extremely imperfect is our knowledge of this subject. As he remarks, it is a matter of extreme difficulty to obtain the temperature of living cetaceans, although this has been taken in the case of a white-whale and a dolphin, which some years ago were kept in confinement in a pond in the United States. With the larger whales such a mode of procedure is, however, obviously quite impracticable, and we have, accordingly, to rely on post-mortem observations. The layer of blubber by which all cetaceans are protected from cold renders the post-mortem refrigeration of the blood a much slower process than in most mammals, so that such observations have a much higher value than might at first be supposed to be the case. Indeed, the blood-temperature of a specimen of Sibbald's rorqual three days after death still stood at 34° C. The various observations that have been taken have afforded the following results in individual cases: Sperm-whale, 40° C.; Greenland right-whale, 38.8° C.; porpoise, 35.6° C.; liver of a second individual, 37.8° C.; common rorqual, 35.4° Cs; dolphin, 35.6° C. The average blood-temperature of man is 37° C., and that of other mammals 39° C.; while that of birds is 42° C. The record of 40° C. in the case of the sperm-whale seems to indicate that at least some cetaceans have a relatively high temperature.
With the possible exception of one West African dolphin, all the Cetacea are predaceous, subsisting on living animal food of some kind. One kind alone (Orca) eats other warm-blooded animals, as seals, and even members of its own order, both large and small. Many feed on fish, others on small floating crustaceans, pteropods and jelly-fishes, while the principal staple of the food of many is constituted by cuttle-fishes and squids. In size cetaceans vary much, some of the smaller dolphins scarcely exceeding 4 ft. in length, while whales are the most colossal of all animals. It is true that many statements of their bulk are exaggerated, but the actual dimensions of the larger species exceed those of all other animals, not even excluding the extinct dinosaurian reptiles. With some exceptions, cetaceans are generally timid, inoffensive animals, active in their movements and affectionate in their disposition towards one another, especially the mother towards the young, of which there is usually but one, or at most two at a time. They are generally gregarious, swimming in herds or "schools," sometimes amounting to many thousands in number; though some species are met with either singly or in pairs.
Commercially these animals are of importance on account of the oil yielded by the blubber of all of them; while whalebone,. spermaceti and ambergris are still more valuable products yielded by certain species. Within the last few years whalebone has been sold in America for £2900 per ton, while it is also asserted that boo() per ton has been paid for two and a quarter tons at Aberdeen, although there seems to be some degree of doubt attaching to the statement. Soon after the middle of the last century, the price of this commodity was as low as £i 50 per ton, but, according to Mr Frank Buckland, it suddenly leapt up to £620 with the introduction of "crinoline" into ladies' costume, and it has apparently been on the rise ever since. Ambergris, which is very largely used in perfumery, is solely a product of the sperm-whale, and appears to be a kind of biliary calculus. It generally contains a number of the horny beaks of the cuttlefishes and squids upon which these whales chiefly feed. Its market-price is subject to considerable variation, but from £3 to £4 per oz. is the usual average for samples of good quality. In 1898 a merchant in Mincing Lane was the owner of a lump of ambergris weighing 270 lb, which was sold in Paris for about 85s. per oz., or £18,360.
Whalebone Whales.
Existing Cetacea are divisible into two sections, or suborders, the relationships of which are by no means clearly apparent. The first section is that of the whalebone whales, or 1Vlystacoceti, in which no functional teeth are developed, although there are tooth-germs during foetal life. The palate is furnished with plates of baleen or whalebone; the skull is symmetrical; and the nasal bones form a roof to the nasal passages, which are directed upwards and forwards. The maxilla is produced in front of, but not over, the orbital process of the frontal. The lacrymal is small and distinct from the jugal. The tympanic is welded with the periotic, which is attached to the base of the skull by two strong diverging processes. The olfactory organ is distinctly developed. The two halves of the lower jaw are arched outwards, their anterior ends meeting at an angle, and connected by fibrous tissue without any symphysis. All the ribs at their upper extremity articulate only with the transverse processes of the vertebrae; their capitular processes when present not articulating directly with the bodies of the vertebrae. The sternum is composed of a single piece, and articulates only with a single pair of ribs; and there are no ossified sternal ribs. External openings of nostrils distinct from each other. longitudinal. A short conical caecum.
When in the foetal state these whales have numerous minute teeth lying in the dental groove of both upper and lower jaws. They are best developed about the middle of foetal life, after which they are absorbed, and no trace of them remains at the time of birth. The whalebone does not make its appearance until after birth; and consists of a series of flattened horny plates, between three and four hundred in number, on each side of the palate, with a bare interval along the middle line. The plates are placed transversely to the long axis of the palate, with short intervals between them. Each plate or blade is somewhat triangular in form, with the base attached to the palate and the apex hanging downwards. The outer edge of the blade is hard and smooth, but the inner edge and apex fray out into long bristly fibres, so that the roof of the whale's mouth looks as if covered with hair, as described by Aristotle. At the inner edge of each principal blade are two or three much smaller or subsidiary blades. The principal blades are longest near the middle of the series, and gradually diminish towards the front and back of the mouth. The horny plates grow from a fibrous and vascular matrix, which covers the palatal surface of the maxillae, and sends out platelike processes, one of which penetrates the base of each blade. Moreover, the free edges of these processes are covered with long vascular thread-like papillae, one of which forms the central axis of each of the hair-like fibres mainly composing the blade. A transverse section of fresh whalebone shows that it is made up of numbers of these soft vascular papillae, circular in outline, and surrounded by concentrically arranged epidermic cells, the whole bound together by other epidermic cells, that constitute the smooth (so-called "enamel") surface of the blade, which, disintegrating at the free edge, allows the individual fibres to become loose and assume a hair-like appearance.
Whalebone really consists of modified papillae of the mucous membrane of the mouth, with an excessive and horny epithelial development. The blades are supported and bound together for a certain distance from their base, by a mass of less hardened epithelium, secreted by the surface of the palatal membrane or matrix of the whalebone in the intervals of the plate-like processes. This is the "gum" of the whalers. Whalebone varies much in colour in different species; in some it is almost jet black, in others slate colour, horn colour, yellow, or even creamy-white. In some descriptions the blades are variegated with longitudinal stripes of different hues. It differs also greatly in other respects, being short, thick, coarse, and stiff in some cases, and greatly elongated and highly elastic in those species in which it has attained its fullest development. Its function is to strain the water from the small marine molluscs, crustaceans, or fish upon which the whales subsist. In feeding, whales fill the immense mouth with water containing shoals of these small creatures, and then, on closing the jaws and raising the tongue, so as to diminish the cavity of the mouth, the water streams out through the narrow intervals between the hairy fringe of the whalebone blades, and escapes through the lips, leaving the living prey to be swallowed.
Although sometimes divided into two families, Balaenidae and Balaenopteridae, whalebone-whales are best included in a single family group under the former name. The typical members of this family are the so-called right-whales, forming the genus Balaena, in which there are no folds on the throat and chest, and no back-fin; while the cervical vertebrae are fused into a single mass. The flippers are short and broad, with five digits; the head is very large and the whalebone very long and narrow, highly elastic and black; while the scapula is high, with a distinct coracoid and coronoid process. This genus contains the well-known Greenland right-whale (B. mysticetus) of the Arctic seas, the whalebone and oil of which are so much valued in commerce, and also other whales, distinguished by having the head somewhat smaller in proportion to the body, with shorter whalebone and a larger number of vertebrae. These inhabit the temperate seas of both northern and southern hemispheres, and have been divided into species in accordance with their geographical distribution, such as B. biscayensis of the North Atlantic, B. japonica of the North Pacific, B. australis of the South Atlantic, and B. antipodarum and novae-zelandiae of the South Pacific; but the differences between them are so small that they may probably be regarded as races of a single species, the black whale (B. australis). On the head these whales carry a peculiar structure which is known to whalers as the "bonnet." This is a large horny excrescence, worn into hollows like a much-denuded piece of limestone rock, growing probably in the neighbourhood of the blow-hole. More than one theory has been suggested to account for its presence. One suggestion is that it indicates the descent of whales from rhinoceros-like mammals; another that this species of whale is in the habit of rubbing against rocks in order to free itself from barnacles, and thus produces a kind of corn - although why on the nose alone is not stated. Dr W. G. Ridewood, however, considers that the structure is due to the fact that the horny layers which are produced all over the skin are not shed on this particular spot.
The pigmy whale (Neobalaena marginata) represents a genus agreeing with the right-whales in the absence of throat-flutings, and with the rorquals in the presence of a dorsal fin. The cervical vertebrae are united, and there are only 43 vertebrae altogether. The flippers are small, narrow, and with only four digits. The ribs remarkably expanded and flattened; the scapula low and broad, with completely developed acromion and coracoid processes. The whalebone is long, slender, elastic and white. The species which inhabits the South American, Australian and New Zealand seas is the smallest of the whalebone-whales, being not more than 20 ft. in length.
In contrast to the preceding is the great grey whale (Rachianectes glaucus) of the North Pacific, which combines the relatively small head, elongated shape, and narrow flippers of the fin-whales, with the smooth throat and absence of a back-fin distinctive of the rightwhales. The whalebone is shorter and coarser than in any other species. In the skeleton the cervical vertebrae are free, and the first two ribs on each side expanded and united to form a large bony shield. In the humpback-whale (Mega.ptera longimana or boops) the head is of moderate size, the whalebone-plates are short and wide, and the cervical vertebrae free. The skin of the throat is fluted so as to form an expansible pouch; there is a low back-fin; and the flippers, which have four digits each, are extremely long, equalling about one-fourth the total length of the animal. The acromion and coracoid processes of the scapula are rudimentary. See Humpback-Whale.
The right-whales are built for cruising slowly about in search of the shoals of small floating invertebrates which form their food, and are consequently broad in beam, with a float-shaped body and immovable neck. The humpback is of somewhat similar build, but with a smaller head, and probably attains considerable speed owing to the length of its flippers. The finners, or rorquals (Balaenoptera), which prey largely on fish, are built entirely for speed, and are the ocean greyhounds of the group. Their bodies are consequently long and attenuated, and their necks are partially mobile; while they are furnished with capacious pouches for storing their food. They chiefly differ from the humpback by the smaller head, long and slender build, small, narrow, and pointed flippers, each containing four digits, and the large acromion and coracoid processes to the low and broad scapula. Rorquals are found in almost every sea. Among them are the most gigantic of all animals, B. sibbaldi, which attains the length of 80 ft., and the small B. rostrata, which does not exceed 30. There are certainly four distinct modifications of this genus, represented by the two just mentioned, and by B. musculus and B. borealis, all inhabitants of British seas, but the question whether almost identical forms found in the Indian, Southern and Pacific Oceans are to be regarded as specifically identical or as distinct awaits future researches, although some of these have already received distinct names. See Rorqual.
In the report on the zoology of the "Discovery" expedition, published in 1907 by the British Museum, E. A. Wilson describes a whale frequenting the fringe of the Antarctic ice which indicates a new generic type. Mainly black in colour, these whales measure about 20 or 30 ft. in length, and have a tall dorsal fin like that of a killer.
Toothed Whales
The second suborder is represented by the toothed whales, or Odontoceti, in which there is no whalebone, and teeth, generally numerous, though sometimes reduced to as single pair, and occasionally wanting, are normally developed. Unlike that of the whalebone-whales, the upper surface of the skull is more or less unsymmetrical. The nasal bones are in the form of nodules or flattened plates, applied closely to the frontals, and not forming any part of the roof to the nasal passage, which is directed upwards and backwards. The olfactory organ is rudimentary or absent. Hinder end of the maxilla expanded and covering the greater part of the orbital plate of the frontal bone. Lacrymal bone either inseparable from the jugal, or, if distinct, large, and forming part of the roof of the orbit. Tympanic bone not welded with the periotic, which is usually only attached to the rest of the skull by ligament. Two halves of the lower jaw nearly straight, expanded in height posteriorly, with a wide funnel-shaped aperture to the dental canal, and coming in contact in front by a flat surface of variable length, but constituting a symphysis. Several of the anterior ribs with well-developed capitular processes, which articulate with the bodies of the vertebrae. Sternum almost always composed of several pieces, placed one behind the other, with which several pairs of ribs are connected by well-developed cartilaginous or ossified sternal ribs. External respiratory aperture single, the two nostrils uniting before they reach the surface, usually in the form of a transverse subcrescentic valvular aperture, situated on the top of the head. Flippers with five digits, though the first and fifth are usually little developed. No caecum, except in Platanista. The first family, Physeteridae, is typified by the sperm-whale, and characterized by the absence of functional teeth in the upper jaw; the lower teeth being various, and often much reduced in number. Bones of the skull raised so as to form an elevated prominence or crest behind the nostrils. Pterygoid bones thick, produced backwards, meeting in the middle line, and not involuted to form the outer wall of the post-palatine air-sinuses, but simply hollowed on their outer side. Transverse processes of the arches of the dorsal vertebrae, to which the tubercles of the ribs are attached, ceasing abruptly near the end of the series, and replaced by processes on the body at a lower level, and serially homologous anteriorly with the heads of the ribs, and posteriorly with the transverse processes of the lumbar vertebrae. Costal cartilages not ossified.
The first group, or Physeterinae, includes the sperm-whale itself, and is characterized by the presence of a full series of lower teeth, which are set in a groove in place of sockets, the groove being imperfectly divided by partial septa, and the teeth held in place by the strong, fibrous gum. No distinct lacrymal bone. Skull strikingly asymmetrical in the region of the nasal apertures, in consequence of the left opening greatly exceeding the right in size.
In the sperm-whale ((Physeter macrocephalus) the upper teeth are apparently of uncertain number, rudimentary and functionless, being embedded in the gum. Lower jaw with from 20 to 25 teeth en each side, stout, conical, recurved and pointed at the apex until they are worn, without enamel. Upper surface of the skull concave; its posterior and lateral edges raised into a very high and greatly compressed semicircular crest or wall (fig. 2). Zygomatic processes of jugal bones thick and massive. Muzzle greatly elongated, broad at the base, and gradually tapering to the apex. Lower FIG. 2. - Skull of Sperm-Whale (Physeter macrocephalus). jaw exceedingly long and narrow, the symphysis being more than half the length. Vertebrae: C 7, D Ii, L 8, Ca 24; total 50. Atlas, or first vertebra, free; all the other cervical vertebrae united by their bodies and spines into a single mass. Eleventh pair of ribs rudimentary. Head about one-third the length of the body; very massive, high and truncated, and rather compressed in front; owing its huge size and form mainly to the accumulation of a mass bf fatty tissue filling the large hollow on the upper surface of the skull and overlying the long muzzle. The single blow-hole is longitudinal, slightly S-shaped, and placed at the upper and anterior extremity of the head to the left side of the middle line. The opening of the mouth is on the under side of the head, considerably behind the end of the snout. Flippers short, broad and truncated. Dorsal fin represented by a low protuberance. See Sperm-Whale.
In the lesser or pigmy sperm-whale (Cogia breviceps) there may be a pair of rudimentary teeth in the upper jaw, while on each side of the lower jaw there are from 9 to 12 rather long, slender, pointed and curved teeth, with a coating of enamel. Upper surface of the skull concave, with thick, raised, posterior and lateral margins, massive and rounded at their anterior terminations above the orbits. Muzzle not longer than the cranial position of the skull, broad at the base, and rapidly tapering to the apex. Zygomatic process of the jugal rod-like. Lower jaw with symphysis less than half its length. Vertebrae: C 7, D 13 or 14, L and Ca 30; total 50 or 51. All the cervical vertebrae united by their bodies and arches. The head is about onesixth of the length of the body, and obtusely pointed in front; the mouth small and placed far below the apex of the snout; the blow-hole in the middle line and in front; their outer edges, especially that of the right, expanded over the front of the inner border of the maxilla. Very high longitudinal crests on the maxillae at the base of the beak, extending backwards almost to the nostrils, approaching each other in the middle line above; sometimes compressed and sometimes so massive that their inner edges come almost in contact. Preorbital notch distinct, and mesethmoid cartilage slightly ossified. Vertebrae: C 7, D 9, L 10, Ca 19; total 45. All the cervical vertebrae united. Upper surface of the head in front of the blowhole very prominent and rounded, rising abruptly from above the small, distinct snout. Two species are known. See Bottle-Nose Whale.
The typical representative of the beaked whales is Ziphius cuvieri, in which there is a single conical tooth of moderate size on each side close to the anterior extremity of the lower jaw, directed forwards and upwards. Skull with the premaxillae immediately in front and at the sides of the nostrils expanded, hollowed, with elevated lateral margins, the posterior ends rising to the vertex and curving forwards, the right being considerably more developed than the left. The conjoint nasals form a pronounced symmetrical eminence at the top of the skull, projecting forwards over the nostrils, flat above, prominent and rounded in the middle line in front, and separated by a notch on each side from the premaxillae. Preorbital notch not distinct. Rostrum (seen from above) triangular, tapering from the base to the apex; upper and outer edges of maxillae at base of rostrum raised into low roughened tuberosities. Mesethmoid cartilage densely ossified in adult age, and coalescing with the surrounding bones of the rostrum. Vertebrae: C 7, D ro, L 10, Ca 22; total 49. The three anterior cervical vertebrae united, the rest free.
In the numerous species of the allied genus Mesoplodon there is a much-compressed and pointed tooth in each half of the lower jaw, FIG. 4. - Sowerby's Beaked Whale (Mesoplodon bidens). variously situated, but generally at some distance behind the apex; its point directed upwards, and often somewhat backwards, occasionally developed to a great size. In the skull the region round the nostrils is as in Hyperoodon, except that the nasals are narrow and more sunk between the upper ends of the premaxillae; like those of Hyperoodon, they are concave in the middle line in front and above. No maxillary tuberosities. Preorbital notch not very distinct. Rostrum long and narrow. Mesethmoid in the adult ossified in its entire length, and coalescing with the surrounding bones. Vertebrae: C 7, D 10, L 10 or II, Ca 19 or 20; total 46 to 48. Two or three anterior cervicals united, the rest usually free.
