from North-w<'stern Patagonia. 207 



reaching to the level of the second infoinnl re-entrant notch 

 of /,.'. 



Incisors about norniul, thoir ixu^lo in tht; type 72°. Molars 

 InigHF than iu xantliorliinun ; »»* with an unusually well- 

 niiirkcd unterior median notch. 



Diniensioiid of the typ*; : — 



ll»ail and body 85 nun. ; tail r)G ; hind foot 18; 

 ear 12. 



Skull: greatest lon<^th 2t'/); condylo-incisive length 22; 

 zygomatic br<iidth 12'G ; nazals D; interorhital breadth -t ; 

 breadth of brain-cade 11*3 ; palatilar length 10 ; palatal 

 fi)rainina 0'8 ; podtforaniiiiul palate WC) ; ujipor niular 

 serit'8 -lO. 



Ilab. as above. 



Ty^>e. Young adult female. B.M. no. IS. 12. 2. iJI. 

 Original number 206. Collected 4th May, 1918. 



" Caught among furze-bushed (' retamos')." — E. B. 



12. Akodon canescens^ Waterh. 



(J . 124, 127, 13.J, 145, 15t;, l.'iS, 168, IC'J, 170 ; ? . 121, 

 122, 141, 143, 167. rilciintu, lJp|)er Rio Negro. 1400 ni. 



? . 216, 221. Maiten, VV. Chubut. 700 m. 



Although I provisionally use canescetift for these greyish 

 mice of the " 13" group — since they correspond with the typii 

 of that name, — I strongly suspc-ct that they are merely the 

 gr«'y seasonal phase of the yellowish xanihorhinus, the latter 

 name having priority. But, though not inconsiderable, our 

 material does not sutfice to settle tiie question with certainty, 

 !ind until such certainty is arrived at it is better not to assume 

 so great a seasonal ehan<;e as the absolute identilication of 

 canescens with .vanthvrhinus involves. A somewhat similar 

 change is recorded by Dr. Allen, though his remarks are 

 difficult to utilize fully, owing to a doubt as to how far 

 .specimens referable to A. iuiscalus are included in what he 

 calls cattisceiis. 



13. Chelemys vestitiis, Thos. 



? . 72. Beatrix, Nahuel Huapi. 



This single specimen is young, and therefore does not 

 tinnish any iuformation as to the relationship uf Ch. vesdtits 

 to the more northern Ch. macronyx of .Sau K;ifaol, Mendoza. 



14. Oeo.tus (gen. nov.) vahiivianusj Phil. 



cJ. 92, 94, 98, 114 ; ? . 8S, 94, 9:., 96. Beatrix, Nahuel 

 Iluapi. 800 m. 



