408 O. C. Marsh — Restoration of Elotherium. 



The type specimen, although incomplete, includes portions 

 of the skull, with various vertebrae and bones of the limbs and 

 feet, and these were sufficient to determine the general form 

 and proportions of the animal here restored. The additional 

 specimens used are mostly in good preservation, and some of 

 them are almost as perfect as in life. Hence, the skeleton, 

 as represented on Plate IX, is believed to be correct in all 

 its essential features. 



Looking at the skeleton, as here shown, it is evident 

 that the most striking features are the large and peculiar 

 skull, and the elongate and slender limbs and feet, characters 

 that do not in themselves suggest the suilline affinities of the 

 animal, which a closer study brings to light. The most nota- 

 ble points in the skull, as here indicated, are the long, pendent 

 process of the malar bone, characteristic of some of the sloths, 

 and the strong projections on the lower jaw. The latter sup- 

 plement the malar process, but are developed to a greater 

 degree than in any other mammals. Another feature of the 

 skull to which the writer has already called attention is the 

 very small brain-case, which proves that the brain itself was 

 very diminutive. This was also true of the other known spe- 

 cies, and was probably the main reason which led to the 

 early extinction of the whole group. 



The slender, highly specialized limbs and feet are likewise 

 particularly noticeable in the restoration. They indicate 

 clearly that the animal was capable of considerable speed, and 

 this must have been of great service as a protection from its 

 enemies. It will be seen that in each foot there are only two 

 functional digits, corresponding to the third and fourth in 

 man. The first digit is entirely wanting, and only remnants 

 remain of the second and fifth. 



Such reduction was, of course, a gradual process, extending 

 over long geological periods. It indicates clearly a change of 

 environment from the swampy home of the primitive five-toed 

 suilline to the elevated, firm upland of later times, over which 

 the present species and its uear allies doubtless roamed. A 

 parallel instance, still more striking, is seen in the gradual 

 change which took place in the equine mammals, as first shown 

 by the writer more than twenty years ago.* 



The Elotheridm were evidently true suillines, but formed a 

 collateral branch that became extinct in the Miocene. They 

 doubtless branched off in early Eocene time from the main 

 line, which still survives in the existing swine of the old and 

 new worlds. 



Yale University, New Haven, Conn., April 12, 1894. 



* This Journal, vol. vii, p. 257, March, 1874. 



