248 PROCEEDINGS OF THE ACADEMY OP 



A large atlas, perhaps belonging to the same animal as the 

 former siDecimeu, measures five inches in breadth between the 

 outer prominent borders of the articuhir concavities for the occi- 

 pital condj'les, and it is about four and a half inches from the 

 neural tubercle to the hypapoph3'sis. It differs in several impor- 

 tant points from the atlas of the rhinoceros, horse, ox, etc., and the 

 want of sufficient means of comparison prevents a determination 

 of its near relationship. 



Another fossil, labelled "Alkali Flats," consists of the greater 

 part of the crown apparently of a last upper premolar or perhaps 

 of a transverse pair of lobes of a true molar, of an animal as 

 large as that to which the preceding specimens belonged. The 

 tooth approaches in character the corresponding portion in the 

 oreodonts, but differs in the proportion atel}'^ less degree of devel- 

 opment of the inner lobe of the crown as compared with the 

 outer one, and in the greater degree of development of the inner 

 basal ridge. The crown measures an inch and a third in trans- 

 verse diameter. These fossils appear to indicate an unknown 

 pachyderm, which may be designated by the name of Hadrohyus 



SUPREMUS. 



Among the Oregon fossils there are a number of imperfect re- 

 mains, of which it was formerly remarked, they indicated at least 

 two species of rhinoceros. One of these was thought to be the 

 same as the R. occidenfalis ; the other was suspected to be the 

 same as the Californian species, B. hesperius. Some additional 

 specimens indicate the second species to have been intermediate in 

 size to that last named, and the R. crassus of the Niobrara River. 

 One of the specimens from Bridge Creek, consisting of a mutilated 

 upper jaw fragment with portions of the fangs of the true molars, 

 shows these to have occupied a space of about five inches. An 

 isolated tooth, from Alkali Flat, apparently a last upper premolar, 

 probably belongs to the same animal. From the outer part of 

 its crown three folds project into the bottom of the median valley. 

 The tooth measures 1 inch and 10 lines wide. The species may 

 be named Rhinoceros pagificus. 



Another fossil specimen, labelled " Crooked River," consists 

 of an isolated vertebral plate of a large turtle, apparently the 

 eighth bone of the series. It has the same shape as in Sti/lemys 

 niohrarensi's^ but is proportionately much shorter in relation 

 with its breadth. It measures 2 inches wide, 1 inch 1 lines long, 

 and 7 lines thick. The specimen probably indicates an unde- 

 scribed species, which may be named Stylemys oregonensis. 



Two additional fossils are brain casts, probably of Oreodon 

 superbus. The cerebral hemispheres are 10 inches 8 lines long, 

 and together about 2^ inches broad. 



[January 16, 



