128 



TKICHECID.E. MAMMALIA. TRICHECIDA. 



quently imparting a very peculiar, if not hideous aspect 

 (fig. 39). In the female there is no trace of this singular 

 apparatus. The canine teeth are large, thick, rather 

 sharply pointed, and curved upwards ; the molars being 

 furnished with simple, conical, and irregularly con- 

 stricted conical crowns. The Elephant-seal enjoys a 

 wide geographical distribution in the southern hemi- 

 sphere, being found on the coasts of Australia, Kergue- 

 land's Land, the Falklands, and other islands both of 

 the South Pacific and Atlantic oceans. It is greatly 

 valued on account of the large quantity of oil which it 

 yields; and, although powerful, it is a comparatively 

 harmless animal, and easily destroyed. Its skin is very 

 thick, and, from its durability when prepared, is much 

 employed in making carriage harness. The habits of 

 the Sea-elephant are somewhat peculiar, inasmuch as 

 it frequents the mouths of rivers, resorting betimes to 

 fresh-water swamps and inland lakes. The male is said 

 to utter when attacked a strange, hoarse, gurgling, wild 

 sound ; the voice of the female having some resemblance 

 to the bellowing of an ox. A sailor once lost his life 

 from the violence of an enraged female, in whose pre- 

 sence he had the cruel folly to skin her young one. 

 The dam generally produces two cubs at a birth, the 

 growth of which is so astonishingly rapid, that in eight 

 days they have doubled their natal dimensions. The 

 period of gestation is believed to be between nine and 

 ten months. 



FAMILY II. TPJCHECIDjE. 



Externally, the members of this family, as originally 

 established, have a general resemblance to the ordinary 

 seals ; but in the form and arrangement of the teeth 

 there are differences of the most marked kind. The 

 cranium is also very unlike that of the typical Phocida? ; 



Fig. 40. 



Skull and section of the lower jaw of the Walrus. 



but in certain of the aberrant genera, this variation is 

 less conspicuous. We have shown this to be the case, 

 especially, in the genus Halichcerus, which is even 

 associated with the present family in the systematic 

 classification of Dr. J. E. Gray. On carefully examin- 



ing the skull of a walrus (fig. 40), the first thing that 

 strikes one is the massive character of all the bones, 

 more particularly those of the anterior part of the face. 

 All the facial modifications here witnessed have refer- 

 ence to the enormously developed tusks ; and, conse- 

 quently, it is in the superior maxillary bone that the 

 more striking morphological changes have taken place. 

 The extension upwards and downwards, as well as the 

 great breadth of this osseous mass, has become neces- 

 sary, in order to insure the reception and fixation of the 

 base of this rootless and huge canine tooth the socket, 

 of course, being extremely capacious. This curious 

 osteological change of form has also had the effect of 

 producing an unusually broad muzzle, tilting up, as 

 it were, the aperture of the nostrils. Scarcely less 

 remarkable is the correlative effect produced by these 

 huge canines on the shape of the lower jaw ; but here, 

 instead of increasing the width, we find the anterior 

 part of the bone much narrowed and compressed, so as 

 to pass securely forward, between and beyond the not 

 very widely separated tusks an arrangement which 

 has likewise involved corresponding peculiarities in the 

 dental formula of the adult animal. According to the 

 investigations of Macgillivra}^ Rapp, Wiegman, and 

 others, there are either ten or twelve incisors, four 

 canines, and eighteen or twenty molars in the young 

 animal ; out of these, two grinders, the lower pair of 

 canines, and all the incisors are deciduous, their sockets 

 at length becoming entirely obliterated. We have thus 

 left behind in the full-grown animal only sixteen per- 

 manent molars, besides the two tusks developed from 

 the upper jaw ; the former are depressed, obliquely 

 truncated, and flat on the crowns; while the tusks, 

 which are directed downwards with a slight curving 

 inwards, measure from fifteen to twenty or twenty-five 

 inches in length, weighing between eight and ten pounds 

 each ; they are also proportionately thick. The cranial 

 cavity is small when compared with that of the typical 

 Phocidae. 



THE WA1ETJS (Trichechiis Rosmarus), or MORSE 

 Plate 13, fig. 42 is the only representative of the 

 present family, if we are content to adhere to the 

 arrangement above given. It is a large, bulky animal, 

 the body usually measuring from ten to fifteen feet in 

 length, and, in the case of the males, as much some- 

 times as twenty feet. The fur is of a deep brownish- 

 black colour, becoming lighter as age advances. The 

 head is comparatively small, terminating anteriorly in 

 an abrupt snout, which is tumid at the sides and 

 clothed with long and very stout whiskers. The lips 

 arc; particularly thick, while the nostrils are rounded 

 and placed high up on the summit of the muzzle. The 

 auditory apertures are placed well back, but there is nc 

 trace of an external auricle; the eyes are comparatively 

 small. The limbs are short, terminating in broad 

 pentadactylous paddles or flippers, having strong 

 interdigital webs. Sir Everard Home's notion that 

 they possessed the power of producing a vacuum to 

 aid the action of climbing, is entirely erroneous. The 

 Walrus is an inhabitant of the shores of the Arctic 

 ocean, being especially abundant on the coasts of 

 Spitzbcrgen, Nova Zembla, and Behring's Straits. 

 These animals congregate together in herds, varying is 



