COPE.] PALEONTOLOGY MIOCENE PERIOD. 485 



It is probable tbat both sexes of these species are horned. This is 

 the case with all of the crauia which I obtained in which the nasal region 

 is not wanting, and donbtless many of these are females. The only one 

 which I obtained with reduced horns is one of the largest size, {S^. heJo- 

 ceras^) and does not probably represent the only female of the collection. 



The general appearance of these species when liviug must have com- 

 bined features of the rhinoceros and elephant in almost equal propor- 

 tions. The length of the femur indicates that the first joint of 

 the leg was free from the abdominal integument, and that some of 

 the species stood higher on the legs than the riiinoceros. There is 

 indication of a trunk, probably a short one, since the neck is not 

 so remarkably shortened as to render this organ absolutely neces- 

 sary. The indications are: the massive borders of the nasal meatus 

 separated laterally from the face by a vertical, obtuse angle; the- 

 great stoutness and shortness of the free end of the nasals, which mucli 

 resemble the same region in the elephant ; and the reduction of the pre- 

 maxillary region and its teeth. It is altogether probable that it had no 

 great length, resembling, perhaps, that of the tapir. These views are 

 in accordance with those already expressed by Professor Marsh in his 

 description of Brontotherium ingens.* Professor Leidy had previously 

 inferred a short proboscis for the Megaceratops coloradoenesis. As com 

 pared with the Eohasileidce of the Eocene, their appearance must have 

 been less exceptional. The proboscidian foot, with short neck, reproduced 

 the elephant; while the narrow head, with the posteriorly placed horns, 

 and the very elongate muzzle, gave these a more snilline expression 

 than the symborodons. The powerful horns, admirably situated for 

 effective use, did not avail to secure their survival beyond the Miocene 

 period more surely than did the laniary tusks of the Eobasileidce in 

 conquering for them a place in the ages that succeeded the Eocene. As 

 the most powerful of the Ungulata of the Miocene, they were the legiti- 

 mate successors of the EohasileidcB^ of the Eocene, as these were of 

 the great laud-saurians of the Cretaceous. A few mastodons and 

 elephants contested with them the supremacy of the Miocene, and 

 held it without rivals in the Pliocene; but why the less formidable 

 rhinoceros should have continued with them, while the Symborodons dis- 

 ai>peared, is a problem whose solution cannot yet be conceived. 



The material on which the above determinations and deductions are 

 based is abundant. The expedition obtained portions of fifty individuals, 

 probably referable to this genus, and twenty-five complete or fragment- 

 ary crania. Those certainly determined belong to the species in the 

 following proportion : S. hucco, 3 ; 8. torvus, 2 ; S. altirostriSj 2 ; S. acer, 3 ; 

 ;S^. heloceras, 1 ; 8. irigonoceras^ G ; 8. ojihryas, 1. Crania of 8. hiicco and 8. 

 rtcer were obtained with mandibles associated; the other species were 

 not: nevertheless, it is probable that some of the various mandibles 

 found separately pertain to the most abundant, 8. trigonoccras. 



Symboeodon bucco, Cope, iSynop. New Vert. Col., 1873, 10. 



The largest species of the genus approaching- nearly the living ele- 

 phant in size. Represented by an imperfect cranium ; by a cranium 

 almost perfect, including, very probably, both mandibular rami, witli 

 entire dentition; a fragmentary skeleton, including parts of cranium, 

 teeth, and vertebrte. The crania are very depressed in form, and exhibit 

 a peculiarity in the horizontal expansion of the malar bones, and tho 

 still greater enlargement of the zygomatic processes of the squamosal. 



*Aiiier. .Journ. Sci. Arts, lb74, p. . 



