SIVATHEEIUM GIGANTEUM. 261 



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 Siva- 

 therium was invested with a trunk like the Tapir. 



This conclusion is further borne out by other analogies, 

 although more indirect than that afibrded by the nasal bones. 



1st. — The large size of the infra-orbital foramen. In 

 the fossil the exact dimensions are indistinct, from the margin 

 having been injured in the chiselling off of the matrix of stone; 

 the vertical diameter we make out to be 1*2 inch, which, per- 

 haps, may be somewhat greater than the truth, but anything 

 approaching this size would indicate a large nerve for trans- 

 mission, 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 into vertical plates, forming large cells, as in the cra- 

 nium of the Elephant, and the occipital is expanded laterally 

 into alee, with a considerable hollow between, as in the Ele- 

 phant. Both these conditions are modifications of structure, 

 adapted for supplying an extensive surface for muscular at- 

 tachment, and imply a thick fleshy neck, with limited range 

 of motion ; and, in more remote sequence, go to prove the 

 necessity of a trunk. 



3rd. — The very large size of the occipital condyles, which 

 are greater, both in proportion and in actual measurement, 

 than those of the Elephant, the interval between their outer 

 angles, taken across the occipital foramen, being 7*4 inches. 

 The atlas and the rest of the series of cervical vertebrae must 

 have been of proportionate diameter to receive and sustain 

 the condyles, and surrounded by a large mass of flesh. Both 

 these circumstances would tend greatly to limit the range 

 of motion of the head and neck. But to suit the herbivorous 

 habits of the animal, it must have had some other mode of 

 reaching its food, or the vertebrae must have been elongated 

 in a ratio to their diameter, sufficient to admit of free motion 

 to the neck. In the latter case the neck must have been of 

 great length, and to support it and the load of muscles about 

 it, an immense develoj)ment would be required in the spinal 

 apophysis of the dorsal vertebrae, and in the whole anterior 

 extremity, with an unwieldy form of the body generally. It 

 is, therefore, more probable that the vertebrae were condensed 

 as in the Elephant, and the neck short and thick, admitting 

 of limited motion to the head, circumstances indirectly cor- 

 roborating the existence of a trunk. 



4th. — The face is short, broad, and massive, to an extent 



h 



