1 98 MAMMALS. 



are bilophodont (two-ridgod), a structure peculiar to some of the Paclij'dcrms, Edentates, and Mar- 

 supials, e.g., tlie Tapir, Megatherium, Diprotodon, and Kangaroo ; as in the Elephant, thej^ are packed 

 in a sort of inner case, or matrix, within the bone ; and as in it they advance continuously from 

 behind forwards, the foremost dropping out, and the vacant alveoli being gradually absorbed suc- 

 cessively, and the roots of the teeth themselves being gradually absorbed as they come to the front, 

 so that they droj) readily out.* Their ear-bones are large, like cetolites, but any inference favourable 

 to their cetaceous character which might be drawn from that fact, is negatived by their still greater 

 resemblance to those of the Hippopotamus ; f and as in the Pachyderms, the anterior part of the 

 head of the first rib articulates with a fovea on the seventh cervical vertebra. Their generative 

 and renal systems are those of the Pachyderms. The teats are placed on tlie breast as in the 

 Elephant, and not far back on the belly as in the "VVliales. They have a neck which the "Whales 

 have not. They have thick fleshy lips, and, like the Elephant, the skin carries more or less 

 numerous hairs or bristles. The coat in which the Rhytina is inclosed is a close agglomeration 

 of hairs or horny tubes, so hard as to resist the blows of an axe, reminding us of the horn of the 

 Rhinoceros. The bones, too, are dense and heavy, while those of the Whales are light and spongy. 



DiNOTHERiuM. Everj^ one must remember the figure of this animal as restored, reposing on 

 the bank of a tranquil lake, with good sturdy Ele^jhant-likc limbs ingeniously tucked up beneath it, 

 but with the termination of one which could not be well got out of the way, modestly concealed 

 by a tuft of grass ; with enormous tusks in its lower jaw bent downwards like the upper tusks of 

 the "Walrus, and clothed in flesh, aU but the points, like an old lady's fingers in mittens with the 

 tips cut ofl'; and finished oflf with a double-chinned proboscis flourishing about in the air in an 

 insane-looking manner. One is happy to think that it was a human artist, not -nature, that 

 devised this curiosity. 



Professor Owen, resting chiefly on the close relation manifested by this extinct genus to the 

 Mastodon in its molar teeth and its inferior tusks, placed it among the Proboscideans ; another 

 proof, by the way, of the pachydermatous relations of this family. He believed it to be a quadrupedal 

 and terrestrial Pachyderm, with thick and stout extremities adapted to the support and progression 

 of the massive frame which characterizes the known Proboscidean Pachyderms. J 



But De Blaiuville and Gooffroy St. Hilaire, from a consideration of the whole cranial and 

 and dental system, came to the conclusion, that it did not possess a proboscis, and, from the 

 resemblance of the fore part of the head to that of the Manatee, that it was an aquatic animal 



* Cuvier figures the African Manatee with six molars were obtained from the Dju-dju of a native chief; the 



in each jaw on each side, and the American with nine, Manatee being, lilve the sturgeon witli ourselves, a perqui- 



which are never all in use at one time, the greatest num- site of royalty. 



ber being seven so in use. Vogel gives the numbers in t So great is their resemblance to those of the Hippo- 



thc Ajah as five, which Owen thinks may be due to the potamus, that Dr. Kirk, seeing a pair of these bones lying 



animal being 3'oung. I possess two fine heads of M. Senega- on my table, from one of the two heads above spoken of, 



LENSis, from Old Calabar, which I owe to the kindness of from the Old Calabar river, took them up with the remark, 



my friend the Rev. W. C. Thomson, of the United Pres- " Hippopotamus' ear-bonesj " with which, of course, he 



I>yterian Mission there. These two differ in the dentition, was familiar. It was he who drew my attention to the 



having respectively nine and ten teeth on each side of each mode of the loss of the anterior teeth — the absorption of 



jaw ; the teeth fully exposed and in use on the diflerent sides the alveoli and of the roots (the posterior roots being 



of the jaw are unequal in number — nine and ten in the absorbed first, leaving the anterior to hold the tooth in its 



one, and eight and nine in the other There are still place so long as required). 



two or three undeveloped teeth stowed away in the rear J Owex in "Ann. Nat. Hist." vol. xi. 329, 1843. 



in the matrix or c.x-se which holds them. My specimens 



