ALLEN: mammalia: xMURID^. 77 



6.3; diastema, 7.2; upper molars, 4; greatest breadth, 13; interorbital 

 breadth, 5. 



This species is represented by 35 specimens, five of which are from the 

 Rio Coy, and the rest, except two from the upper Rio Chico, near or 

 within the Cordilleras, two being from the Pacific slope of the Cordilleras ; 

 all were collected by Mr. Peterson. The Rio Coy specimens were taken 

 in November, the Rio Chico specimens at various dates from January 31 

 to March 4. Two additional specimens were taken by Mr. Colburn, one 

 at Swan Lake, March 14, and the other at the Basalt Canons, April 30. 

 The several half grown young in the series are similar in coloration to 

 the adults, except that the brown of the upper parts is rather duller. The 

 adults are very uniform in coloration. 



In Patagonia this species ranges, as shown by the present material, 

 from the coast region westward into the eastern base of the Andes, and 

 probably thence northward. Mr. Peterson refers to it as one of the most 

 common species of the upper Rio Chico region, frequenting the edge of 

 the timber as well as the more open grassy country. He states that the 

 "skin always adheres to the tail very firmly in adults," and most of the 

 specimens show that the skin of the tail was split open to remove it and 

 afterwards sewed up. 



Before the present material came into my hands a number of specimens 

 of this species were sent to Mr. Oldfield Thomas for determination, and he 

 identified them as his Akodon liirtits. When at the British Museum in 1901, 

 I made direct comparison of a number of specimens wdth the type and 

 paratype of A. hiytus. In writing up the history of this species in 1902, 

 under the name Akodon hirtiis, I made the following comment on the case : 



''Akodon hirtus was based on two specimens collected at San Rafael, 

 Mendoza, by Mr. Bridges many years ago, the type and paratype having 

 been skinned from alcoholic specimens. The skins cannot, therefore, be 

 trusted as regards color ; they agree, however, as closely with the upper 

 Rio Chico specimens as could be expected, and the skulls present no 

 appreciable differences. It should be noted, however, that the type locality 

 of the species is about 1,000 miles directly north of the upper Rio Chico 

 region, and it seems more than probable that comparison of a good series 

 of freshly collected skins from the two localities would reveal appreciable 

 differences. The tabulation of the measurements (summarized above) for 

 use in the present connection shows that the dimensions given by Mr. 



