346 GEOLOGICAL SUEVEY OF THE TEEEITOEIES, 



large number of specimens representing so many individuals, consider- 

 able variation in the details of structure have been noticed. The fossils 

 also exhibit great variety in the condition of preservation. Among them 

 are some crushed in such a way as to indicate that the condition was due 

 to the bite of certain of the powerful carnivores which were contempo- 

 raneous with the animals. 



Oreodon gracilis. — A small species, about the size of a musk deer ; was 

 an associate of the former. It was probably equally abundant, but the 

 greater delicacy of its skeleton rendered it more liable to a variety of ac- 

 cidents insuring destruction. 



Oreodon major. — A larger species than either of the former, indicated by 

 a few remains, among them a nearly entire and well-preserved skull, dis- 

 covered by Professor Hayden in the mauvaises terres deposits of White 

 Eiver. The skull measures about ten inches in length \ and the animal was 

 about as large as the ordinary wolf or the largest-sized dog. The species is 

 remarkable for the large size of its ear capsules, which not only greatly 

 exceeded in proportion those of the Oreodon Culbertsoni and O. gracilis, 

 but are larger than in the existing hog. What relationship the inflated 

 or enlarged condition of the ear capsules has with the acuteness of hear- 

 ing or the habits of animals has not been clearly indicated. The com- 

 parative scarcity of the remains of Oreodon major in the localities in 

 which those of the preceding species were obtained leads me to suspect 

 that the former was probably not cotemporaneous with the latter, or 

 at least did not inhabit the same places. 



A few remains from the mauvaises terres of White Eiver, which the 

 writer had referred to two species of oreodon, distinct from the preceding 

 under the names of Oreodon affinis and 0. hybridus, I suspect to have per- 

 tained to hybrids ; probably of 0. gracilis and O. major. 



In 1866, Professor Hayden obtained among a number of remains of 

 Oreodon Culbertsoni, from the mauvaises terres, a specimen of a skull, 

 agreeing in size, form, and details with that of the species just named, 

 except that it had the ear capsules proportionately as well developed as 

 in 0. major. I referred it to a distinct species with the name of Oreodon 

 bullatus, but I suspect it pertained to a hybrid between 0. major 

 and 0. Culbertsoni. It is not unlikely that Oreodon major may have lived 

 in a locality skirting that inhabited by the species 0. Culbertsoni 

 and 0. gracilis. The intimate relationship anatomically and physiolo- 

 gically would readily allow of the hybridization which has been sus- 

 pected. 



Oreodon superbus. — Last autumn the writer received through the 

 Smithsonian Institution, for examination, a collection of mammalian 

 fossils from the Eeverend Thomas Condon, of Dalles City, Oregon. 

 They were mainly collected in the valley of Bridge Creek, a tributary of 

 John Day's Eiver, Oregon. The fossils in general appearance and con- 

 dition of "petrifaction resemble those of the mauvaises terres of White 

 Eiver, Dakota. 



The greater number and more striking specimens belong apparently 

 to a species of oreodon larger than any of those from the locality last 

 named. The skull of the animal was about fourteen inches in length. 

 The ear capsules are inflated and proportionately as large as in 0. major. 

 The face is rather more abruptly narrowed in advance of the orbits than 

 in the latter ; the infra-orbital arches are proportionately deeper, and 

 the lachrymal depressions are shallower. The teeth have the same con- 

 stitution as in the mauvaises terres oreodons, but the canines and pre- 

 molars are proportionately wider and thinner, and thus appear of a more 

 compressed character. The inferior canine tooth, at the base of the 



