396 imperfectly divided by partial septa, and held in place by the strong, fibrous gum which surrounds them. No distinct lacrymal bone. Cranium strikingly asymmetrical in the region of the narial. apertures, in consequence of the left opening greatly exceeding the right in size. Physctcr. Upper teeth apparently of uncertain number, rudi mentary and functionless, being embedded in the gum. Lower jaw with from 20 to 25 teetli on each side, stout, conical, recurved, and pointed at the apex until they are worn, without enamel. Upper surface of the cranium concave ; its posterior and lateral edges raised into a very high and greatly compressed semicircular crest or wall. Zygomatic processes of malar bones thick and massive. Rostrum greatly elongated, broad at the base and gradually tapering to the apex. Upper edge of the mesethmoid forming a roughened irregular projection between the narial apertures, inclining tD the left side. Mandible exceedingly long and narrow, the symphysis being more than half the length of the ramus. Vertebra: C 7, D 11, FIG. 43. Skull of Sperm Whale (P lyseter macrocephalus). L 8, C 24 ; total 50. Atlas free ; all the other cervical vertebra 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 remarkable form mainly to the great accumulation of a peculiarly modified form of adipose tissue filling the large hollow on the upper surface of the cranium and overlying the rostrum. The single blowhole is longitudinal, slightly sigmoid, 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. Pectoral fin short, broad, and truncated. Dorsal fin a mere low protuberance. There is no certain evidence that more than one species of this genus exists. This is the Cachalot or Sperm Whale, P. macro- ccphalus, one of the most colossal of animals, quite equalling, if not exceeding, the Greenland Whale in bulk. The length of the full-grown male is from 55 to 60 feet, but the female is stated not to reach more than half that size. It feeds chiefly on cephalopods and fish, and is one of the most extensively distributed of Cetaceans, being met with, usually in herds or "schools," in almost all tropical or subtropical seas, but not occurring, except accidentally, in the polar regions. Those that appear occasionally on the British coasts are solitary stragglers, usually, if not always, old males. The oil contained in the great cavity above the skull, when refined, yields " spermaceti," and the thick covering of blubber which everywhere envelops the body produces the valuable "sperm oil" of commerce ; hence this animal has long been the subject of a regular chase, by which its numbers have been greatly diminished. The substance called "ambergris," largely used in perfumery, is a [CETACEA. top of the head anteriorly to the eyes, and to the left of the middle line ; the pectoral fins are obtusely falcate ; and there is a trian gular dorsal fin. The history of this genus is a good illustration of the difficulties in which the study of the Cctacca has been involved by the super ficial manner in which it has been investigated. The first known example, a skull from the Cape of Good Hope in the Paris Museum, was described by Blainville under the name of 1 hysclcr brei-iccps. This was afterwards with good reason generically separated by Gray. Until within a very few years ago only five othar individuals had been met with, each of which had been described under a different specific name (viz. , grayi, madeayi, simus. floiveri, and potxii), and which are arranged by Gray in two distinct genera. The most careful examination of the description given of these specimens, or of the now numerous osteological remains available, fails to detect any differences beyond those which may be attributed to age or sex ; and hence, according to our present knowledge, these six supposed species must all be included under one name, K. brcriccps, an animal which appears to attain the length of 10 feet when adult, and has been met with at various distant localities in the Southern Ocean, and also off the coast of Madras and in the North Pacific. Subfamily Ziphiinae. Teeth of the mandible quite rudimentary and concealed in the gum, except one, or very rarely two, pairs which may be largely developed, especially in the male sex. A distinct lacrymal bone. Externally the mouth is produced into a slender rostrum or beak, from above which the rounded eminence formed by a cushion of fat resting on the cranium in front of the blowhole rises somewhat abruptly. Spiracle or blowhole single, crescentic, median, as in the JJclphinidee. Pectoral fin small, ovate, the five digits all moderately well developed. A small obtusely falcate dorsal fin situated considerably behind the middle of the back. Longitudinal grooves on each side of the skin of the throat, diverging posteriorly, and nearly meeting in front. In external characters and habits the animals of this group closely resemble each other. They appear to be almost exclusively feeders on various species of cephalopods, and occur either singly, in pairs, or in small herds. By their dental and osteological characters they are easily separated into four distinct genera. Hypcroodon. A small conical pointed tooth at the apex of each ramus of the mandible, concealed by the gum during life. Skull with the upper ends of the premaxilla; rising suddenly behind the nares to the vertex and expanded laterally, their outer edges curving backwards and their anterior surfaces arching forwards and overhang ing the nares ; the right larger than the left. Nasal bones lying in the hollow between the upper extremities of the premaxills, strongly concave in the middle line and in front ; their outer edges, espe cially that of the right, expanded over the front of the inner concretion formed in the intestine of the Sperm Whale, and is found floatin on the surface of the seas which they inhabit. Its genuineness is attested by the presence of the debris of the horny beaks of the cephalopods on which the Whales feed. Kogia, Teeth of the upper jaw absent or reduced to a rudi mentary pair in front ; in lower jaw 9 to 12 on each side, rather long, slender, pointed, and curved, with a coating of enamel. Upper surface of the cranium concave, with thick, raised, posterior and .lateral margins, massive and rounded at their anterior terminations above the orbits. Upper edge of the mesethmoid forming a pro minent sinuous ridge, constituting a kind of longitudinal septum to the base of the great supra-cranial cavity. Rostrum not longer than the cranial portion of the skull, broad at the base, and rapidly tapering to the apex. Zygomatic process of the malar styliform. Mandible with symphysis less than half the length of the entire ramus. Vertebra : C 7, D 13 or 14, L and C 30 ; total 50 or 51. All the cervical vertebra united by their bodies and arches. External characters not well known, but, judging by the somewhat conflicting accounts of those that have had an opportunity of observing them, the head is about one-sixth of the length of the body, and obtusely pointed in front ; the mouth small and placed far below the apex of the snout; the spiracle crescentic, and placed obliquely on the FIG. 44. Hypcroodon rostratus. From a specimen taken off the coast of Scotland, 1882. border of the maxilla. Very high longitudinal crests on the maxillie at the base of the rostrum, extending backwards almost to the nares, approaching each other in the middle line above; sometimes compressed and sometimes so massive that their inner edges come almost in contact. Anteorbital notch distinct. Mesethmoid but slightly ossified. Vertebra : C 7, D 9, L 10, C 19 ; total 45. All the cervical vertebra 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, //. rostratus, the common Hyperoodon or Bottle-nose, and //. latifrons, both inhabitants of the North Atlantic, and attaining when adult respectively the length of 24 and 30 feet. Ziplrius. A single conical tooth of moderate size on each side of the mandible close to the anterior extremity, and directed forwards and upwards. Skull with the premaxillse immediately in front and at the sides of the nares expanded, hollowed, and 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 forming a strongly pronounced sym metrical eminence at the top of the cranium, projecting forwards over the nares, flat above, most prominent and rounded in the middle line in front, and separated by a notch on each side from the premaxilhe. Anteorbital notch not distinct. Rostrum (seen from above) triangular, gradually tapering from the base to the apex ; upper and outer edges of maxillaj 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. Vertebra: C 7, D 10, L 10, C 22 ; total 49. The
three anterior cervical vertebra united, the rest free.