1836.] a new Fossil Genus of the Sivdlik range. 47 



separate in the Yak* and Aurochs. In the Camel, they are also separate, 

 and this animal has greater mobility in the upper lip than is found in other 

 ruminants. 



In the Pachydermata, both these conditions of structure are present 

 and wanting in different genera ; and their presence or absence is accom- 

 panied with very important differences in the form of the corresponding 

 soft parts. It is therefore in this family that we are to look for an expla- 

 nation of what is found in the Sivatherium. 



In the Elephant and Mastodon, the Tapir, Rhinoceros, and Palseothe- 

 rium, there are three pairs of bones to the external nostrils ; the nasals, 

 the maxillaries, and incisivest. In all these animals, the upper lip is 

 highly developed, so as to be prehensile, as in the Rhinoceros, or extended 

 into a trunk, as in the Elephant and Tapir ; the amount of developement 

 being accompanied with corresponding difference in the position and form 

 of the nasal bones. In the Rhinoceros, they are long and thick, extending 

 to the point of the muzzle, and of great strength to support the horns of 

 the animal : and the upper lip is broad, thick, and very mobile, but little 

 elongated. In the Elephant, they are very short, and the incisives enor- 

 mously developed for the insertion of the tusks, and the trunk is of great 

 length. In the Tapir, they are short and free, except at the base, and pro- 

 jected high above the maxillaries ; and the structure is accompanied by a 

 well developed trunk. In the other Pachydermatous genera, there are out 

 two pairs of bones to the external nostrils, the nasals and the incisives : 

 the latter running up so as to join on with the former; and the nasals, 

 instead of being short and salient, with a sinus laterally between them and 

 the maxillaries, are long, and run forward, united to the maxillaries, more 

 or less resembling the nearly parallel slips of the Ruminantia. Of this 

 genera, the Horse has the upper lip endowed with considerable mobility ; 

 and the lower end of the nasals is at the same time free to a small extent. 

 In all the other genera, there is nothing resembling a prehensile organ in 

 the upper lip. 



In the Sivatherium, the same kind of structure holds, as is found in the 

 Pachydermata with trunks. Of these it most nearly resembles the Tapir. 

 It differs chiefly in the bones of the nose being larger and more salient 

 from the Chaffron ; and in there being less width and depth to the naso- 

 maxillary sinus, than the Tapir exhibits. But as the essential points of 

 structure are alike in both, there is no doubt that the Sivatherium was 

 invested with a trunk like the Tapir. 



This conclusion is further borne out by other analogies, although more 

 indirect than that afforded by the nasal bones. 



1st. — The large size of the infra-orbitary foramen. In the fossil, the 

 exact dimensions are indistinct, from the margin having been injui'ed in 

 the chiseling off of the matrix of stone : the vertical diameter we make 

 out to be 1.2 inch, which perhaps may be somewhat greater than the truth ; 

 but any thing approaching this size, would indicate a large nerve for 

 transmission, and a highly developed condition of the upper lip. 



2nd. — The external plate of the bones of the cranium is widely separated 

 from the inner, by an expansion of the diploe in vertical plates, forming 

 large cells, as in the cranium of the Elephant : and the occipital is ex- 

 panded laterally into alas, with a considerale hollow between, as in the 

 Elephant. Both these conditions are modifications of structure, adapted 

 for supplying an extensive surface for muscular attachment, and imply a 

 thick fleshy neck, with limited range of motion ; and, in more remote 

 sequence, go to prove the necessity of a trunk. 



* Cuvier. Ossemens Fossiles, tome iv. p. 131. 

 t Cuvier. Ossemens Fossiles, tome iii. p. 29. 



