1390 CLASS MAMMALIA. 



second pair of prominences placed over the orbit, instead of much 

 further back, as in fig. 1260. 



Writing of the Dinocerata Professor Marsh observes that " the fossil 

 remains of this group have hitherto been found in a single Eocene lake- 

 basin of Wyoming, and none are known from any other part of this 

 country or from the Old World. These gigantic beasts, which nearly 

 equalled the Elephant in size, roamed in great numbers about the borders 

 of the ancient tropical lake, in which many of them were entombed. This 

 lake-basin, now drained by the Green River, the main tributary of the 

 Colorado, slowly filled up with sediment, but remained a lake so long 

 that the deposits formed in it, during Eocene time, reached a vertical 

 thickness of more than a mile. ... At the present time this ancient 

 lake-basin, now 6000 to 8000 feet above the sea, shows evidence of a vast 

 erosion, and probably more than one-half of the deposits once left in it 

 have been washed away, mainly by the action of the Colorado river. 

 What remains forms one of the most picturesque regions in the whole 

 West, veritable mauvaises terres, or bad lands, where slow denudation 

 has carved out cliffs, peaks, and columns of the most fantastic shapes 

 and colours. This same action has brought to light the remains of many 

 extinct animals, and the bones of the Dinocerata, from their great size, 

 naturally first attract the attention of the explorer." • The latter part of 

 this description recalls to mind the very similar conditions of the Plio- 

 cene Siwalik deposits of Northern India, where the place of the bones of 

 Dinocerata is taken by that of Proboscidea. The Professor proceeds to 

 mention that the first remains of these wonderful animals were obtained 

 by him in the year 1870. 



In respect to their structure the same writer observes that in the 

 cranium " each maxillary bone carried a well-developed process, prob- 

 ably of the nature of a horn-core. The nasals support two similar but 

 smaller horn-cores ; and the frontals are developed behind into two larger 

 bony projections, most probably also of the nature of horn-cores. The 

 animal thus possessed three pairs of horn-cores, one carried by the upper 

 jaw-bones, one by the nasals, and one by the frontal bones. Whether, 

 however, these so-called 'horn-cores' really supported horns, of the nature 

 of the horns of the Cavicorn Ruminants, is quite a matter of conjecture ; 

 and there is much probability in the view entertained by Owen — namely, 

 that some of them were simply covered by callous integument." 



As regards the mental powers, Professor Marsh remarks : " The brain- 

 cavity of Uintatherium is perhaps the most remarkable feature in this 

 remarkable genus. It proves conclusively that the brain (fig. 1262, a) 

 was proportionately smaller than in any other known mammal, recent or 

 fossil, and even less than in some reptiles. It is, in fact, the most rep- 

 tilian brain in any known mammal. In U. mi7'abile the entire brain was 

 actually so diminutive that it could apparently have been drawn through 

 the neural canal of all the presacral vertebras, and certainly through the 

 cervicals and lumbars." 



Suborder 7. Proboscidea. — The last of the suborders into 

 which the Ungulates are divided is that of the Proboscidea, repre- 

 sented at the present day solely by the two species of Elephant, 

 but in past epochs including a large number of more or less closely 

 allied forms. These animals are of huge bulk and stout build, and 



