SUPPLEMENT. 303 



36802, 3, 7. Three imperfect mandibular rami ; from Hordwell. 



Presented by S. Laing, Esq.^ 1862' 



Family MICROCHCERID^. 



This family is apparently allied to the Erinaceidw, with which it 

 agrees in the squared crowns of the true molars ; but is distinguished 

 by the arrangement of the tubercles or cusps on the crowns of the 

 hinder cheek-teeth, and by pm. 3 being as complex as pm. 4 . 



The genus Hyopsodus (woodcut, fig. 44), which is regarded by 



ri,-?. 44. 

 a. 



Hyopsodus vicarius, Cope. — The left upper (a) and lower (b) cheek-dentition ; 

 from the (? Bridger) Eocene of Wyoming, U.S.A. |. (From the ' Amer. Nat.') 



some writers as closely allied to the Lemuroidea, should probably be 

 included in the present family ^ ; it is stated to have four premolars. 



Genus MICRO CHGBRUS, Wood ^ 



Dentition :— I. f, C. \, Pm. ?, M. ?, or I. |, C. J-, Pm. ?, M. |. The 



first pair of upper incisors are separated from one another by an 

 interval (as in Erinaceus), but there is no other diastema ; the 

 first four upper teeth are compressed and trenchant, while the 

 last five are quadrangular and tuberculated ; the true molars have 

 four main tubercles with an intervening pair of smaller ones, and a 

 single one on the outer side ; pm. 3 and pm. 4 have two tubercles. 



Microchoerus erinaceus. Wood ^ 

 This is the type species and is about equal in size to Erinaceics 

 europceus. 



Hah. England. 



^ See Quart. Journ. Geol. Soc. vol. xli. p. 529. In that paper the present 

 writer regarded Hyopsodus as probably identical with Microchoerus ; he is, 

 however, informed by Mr. Osborn, of Princeton, New Jersey (who when in 

 England carefully examined the type specimen of Microchoerus)^ that the two 

 appear distinct. 



^ London Geological Journal, no. 1, p. 5 (1846). ^ Loc. cit. 



