STJPPLEJTENT. 335 



line with the posterior edges of the maxillae, and hy the infraorbital 

 foramen being situated above the posterior part of pm. 3 ; and from 

 E. major by the paroccipital process being placed behind the auditory 

 bulla. The following specimen belongs to the variety named paci- 

 ficus by Cope ', which is intermediate between the other two. 

 Hob. North America. 



M. 2558. The cranium, with the dentition in an early stage of wear ; 

 from the Miocene of the John Day Eiver, Oregon, U.S.A. 

 The length of the series of cheek-teeth is 0,091. 



Presented by E. Lydtkker, Esq., 1885. 



Family SUID^E (pt. ii. p. 250). 



Genus HYOTHERIUM (pt. ii. p. 254). 



The writer has come to the conclusion that this genus may pro- 

 bably be regarded as the ancestor both of Dicotyles and Sus 2 . 



Hy otherium perimense, Lydekker 3 . 



This species may be defined as similar in size to H. waterhousei 

 (supra, pt. ii. p. 256), but distinguished by its wider molars, in which 

 respect it approaches E. scemmerringi (supra, pt. ii. p. 257) and the 

 Indian H. sindiense, although differing from the former by the greater 



Fig. 54. 



m. I. in. 2. m. 3. 



Hyoiherium perimense. Part of the left maxilla ; from the Pliocene 

 of Perim Island, India. \. 



width of the lower molars, and from the latter either by its inferior 

 size, or by its wider lower molars, or by both these two characters. 

 Hob. India (Perim Island). 



1 Ibid. p. 519. 



2 Quart. Journ. Geol. Soc. vol. xliii. p. 22 (1887). 



3 Ibid. p. 19. 



