78 PATAGONIAN EXPEDITIONS : ZOOLOGY. 



Thomas for his type of ^. Jiirtiis are much larger (total length 197) than 

 the very largest of a series of over 20 adults from the Rio Chico country. 

 The measurements of the type skull, however, do not exceed those of 

 average adults from the Rio Chico. For the present I follow Mr. Thomas 

 in identifying the Rio Chico specimens, quite a number of which have 

 passed through his hands, with A. hirtttsy 



Since the above was written, however, Mr. Thomas has described an 

 Akodon sitffusits from a point quite near the Rio Chico region and in 

 quite similar country, and, in the absence of authentic specimens of A. 

 suffusus for comparison, it seems quite beyond question that the present 

 series should be referred to A. snffitstts rather than to A. hirtus, described 

 from a point so much further north and from a markedly different region. 



Mr. Thomas, in describing A. suffusus, says: "Closely allied to^. hir- 

 tus, Thos., but the general colour stronger, the belly lighter, and with certain 

 cranial differences detailed below." These are: "Skull in general shape 

 like that of A. hirtus, not elongated as in A. loiigipilis. But it is rather 

 lower and flatter throughout, less rounded and convex along the middle 

 line, especially in the interorbital region." 



I am also indebted to Mr. Thomas for the suggestion, made some time 

 ago, that Hesperomys {Habrothrix) longipHis of Milne-Edwards, as cited 

 above, is probably his Akodon hirttis of later date — now A. sttffusiis. 



Subgenus Chelemys Thomas. 

 Chelemys Thomas, Ann. & Mag. Nat. Hist. (7), XII, Aug., 1903, 242. 

 Type, Hesperomys megalonyx Waterhouse. 



"General characters, skull, and dentition as in Akodon, but the claws, 

 especially the anterior ones, very large, fossorial. . . . 



" Now that the known species have been so considerably multiplied, it 

 seems convenient to have a subgeneric name by which to designate what 

 have hitherto been termed the 'long-clawed Akodons.' " — Thomas, /. c. 



Mr. Thomas formally refers to this subgenus three species, Akodon 

 mega/onyx (the type), A. niacronyx, and A. vestihis. 



Akodon (Chelemys) vestitus Thomas. 



(Plates XI, Fig. 5, Skull; XII, Figs. 9 and 10, Teeth.) 



Akodon [Chelemys) vestitus Thomas, Ann. & Mag. Hist. (7), XII, Aug., 

 1903, 242, "Valle del Lago, Cordillera region of Southern Chubut 

 Territory, Patagonia." 



