SOUTH AMERICA 381 



The rice rat of Narborough Island is described as similar to 

 N. indefessus of Indefatigable but larger, the feet and ears 

 especially larger, the former 31 mm. or greater in length; 

 coloration much darker above, chiefly blackish mixed with 

 some rusty brownish; below, darker gray (Heller, 1904). The 

 skull is wider, with longer nasals and shorter palatal foramina 

 than in the latter. Total length, 303 mm. ; tail, 131 ; hind foot, 

 33; ear, 23. An adult male skull measured 41.5 in length. 



According to Heller's account, "this species was found in- 

 habiting the cracks and fissures in barren black lava fields near 

 the coast of Mangrove Point, Narborough Island. Individuals 

 were rather scarce at this locality, perhaps owing to the paucity 

 of the vegetation. The contents of several stomachs were 

 examined and found to contain a reddish material resembling 

 pulverized Crustacea." At the time of Heller's visit the Euro- 

 pean rats and house mouse apparently had not reached Nar- 

 borough Island. Should they later become established there, 

 it is likely that this native species will suffer. 



SWARTH'S RICE RAT 

 NESORYZOMYS SWARTHI Orr 



Nesoryzomys swarthi Orr, Proc. California Acad. Sci., ser. 4, vol. 23, p. 304, Sept. 1, 

 1938 ("From the vicinity of Sulivan [ = Sullivan] Bay, James Island, Galapagos 

 Islands"). 



FIGS.: Orr, 1938, pi. 25, figs. 1, la (skull). 



This island race is evidently closely related to N. indefessus 

 of Indefatigable Island and is indistinguishable from it in 

 color, but the skull shows broader nasals, a larger rostrum, 

 greater diastema and much larger molariform teeth than any 

 of the other species of the genus yet known. The average 

 measurements of three males are given as: Total length, 312.3 

 mm.; tail, 133.7; hind foot, 35.7; length of skull, 40.6. 



The four specimens from James Island, from which no 

 mammals had previously been known, were collected in 1906 

 by J. S. Hunter for the California Academy of Sciences and 

 may be regarded as the representative form on that island, of 

 the indefessus type, which is again present on Narborough 

 Island in the much darker N. narboroughi. In the 30 years and 

 more since the species was discovered, no other examples have 

 been collected by more recent expeditions, so that, as Orr 

 writes, "the possibility exists that this form may now be 



