ZooL— Vol. III.] HELLER— GALAPAGOS MAMMALS. 



241 



Kesoryzomys new genus. 



Similar to Oryzomys, but interorbital portion of skull 

 very different. The frontal bones medially much narrower, 

 with rounded sides at the interorbital constriction; snout 

 more elongate, the nasals narrower, considerably longer, 

 and less convex in profile; zygomatic width of skull and 

 length of upper molar series much less. The external dif- 

 ferences in Galapagos species consist of considerably 

 shorter fur and tail. 



Type, IV. narboroughi. 



Range. — Galapagos Archipelago (two peculiar species). 



Nesoryzomys indefessus ( Thomas). 



Oryzomys indefessus Thomas, Ann. and Mag. Nat. Hist. ser. 7, v. 4, 1899, 

 p. 280. 



Range. — Indefatigable Island (Rothschild Expedition, 

 Hopkins Expedition), South Seymour Island (Hopkins 

 Expedition). 



An abundant species on Indefatigable Island and South 

 Seymour Island, but lacking on North Seymour. This 

 species seems to be more nocturnal in habits than Oryzomys. 

 It inhabits burrows or rock crevices beneath bushes. 



Measurements of Nesoryzomys indefessus 



