StJPPLEMENT. 



335 



line with the posterior edges of the maxillae, and by 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 j^d^ 

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

 Rah. 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 hy B. LydehTcer, Esq., 1885. 



Family SUID^ (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 ^. 



Hyotherium perimense, Lydekker ^ 



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 H. soemmerringi {supra, pt. ii. p. 257) and the 

 Indian H. sindiense,2X\ho\!i^ diff'ering from the .former by the greater 



Fig. 54. 



m. 1. m. 2. m. 3. 



Hyotherium perime7ise.— Fart 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. 

 Eah. India (Perim Island). 



^ Ibid. p. 519. 



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



3 Ibid. p. 19. 



