AMPHITHEPvIID^. 277 



47785. Hinder part of the right ramus of the mandible, sho^Ying 

 five true molars ; from the same locality. 



Beckles Collection. Purchased, 1876. 



Achyrodon pusillus, Owen\ 

 Distinguished from the preceding species by the structure of the 

 mandible and teeth. 



Hah. Europe (England). 



47747. Eragment of the left ramus of the mandible, containing one 

 {Fig.) tooth ; from the Middle Purbeck group of Durdlestone 

 Bay, Swanage, Dorsetshire. This specimen is the type, 

 and is figured by Owen in his ' Mesozoic Mammalia ' 

 (Mon. Pal. Soc), pi. ii. fig. 8 : at that time there were four 

 cheek-teeth preserved. 



Becldes Collection. Purchased, 1876. 



Specifically undetermined sjyecimen. 



48401. Eragment of a mandibular ramus with four true molars, 

 probably belonging to a small species of the present genus ; 

 from the Middle Purbeck group of Durdlestone Pay, 

 Swanage, Dorsetshire. 



Bechles Collection. Purchased, 1876. 



Genus PERAMUS, Owen \ 



The lower true molars are relatively stouter, and their blade 

 proportionally wider than in either of the preceding genera ; the 

 complete dental formula is unknown. 



Peram-us tenuirostris, Owen ^ 



This is the type species. 

 Hah. Europe (Eugland). 



47743. The left ramus of the mandible, containing the last four 

 {Fig.) cheek-teeth ; from the Middle Purbeck group of Durdle- 

 stone Bay, Swanage, Dorsetshire. This specimen is the 

 type, and is figured by Owen in his ' Mesozoic Mammalia ' 

 (Mon. Pal. Soc), pi. ii. fig. 10. 



BecMes Collection. Purchased, 1876. 



^ Mesozoic Mammalia (Mon. Pal. Soc). p. 39 (1871). 

 2 Ibid. p. 41 (1871). 

 ^ Log. cit. 



