from North-western Patagonia. 207 
reaching to the level of the second internal re-entrant notch 
of m’. 
Incisors about normal, their angle in the type 72°. Molars 
larger than in wanthorhinus; m* with an unusually well- 
marked anterior median notch. 
Dimensions of the type :— 
Head and body 85 mm.; tail 56; hind foot 18; 
ear 12. 
Skull: greatest length 24°5 ; condylo-incisive length 22 ; 
zygomatic breadth 12°6 ; nasals 9; interorbital breadth 4; 
breadth of brain-case 11°33; palatilar length 10; palatal 
foramina 5°8 ; postforaminal palate 3°63; upper molar 
series 4:0. 
Hab. as above. 
Type. Young adult female. B.M. no. 18. 12. 2. 31. 
Original number 206. Collected 4th May, 1918. 
“ Caught among furze-bushes (‘ retamos’).”—WZ. B. 
12. Akodon canescens, Waterh. 
ae LEE 3b 145, VG. 15S, 16S, 169s TO) se ee 
122, 141, 143, 167. Pilcafeu, Upper Rio Negro. 1400 m. 
@. 216,221. Maiten, W. Chubut. 700 m. 
Although I provisionally use canescens for these greyish 
mice of the “* B” group—since they correspond with the type 
of that name,—I strongly suspect that they are merely the 
grey seasonal phase of the yellowish wanthorhinus, the latter 
name having priority. But, though not inconsiderable, our 
' material does not suffice to settle the question with certainty, 
and until such certainty is arrived at it is better not to assume 
so great a seasonal change as the abgolute identification of 
canescens with wanthorhinus involves. A somewhat similar 
change is recorded by Dr. Allen, though his remarks are 
difficult to utilize fully, owing te a doubt as to how far 
specimens referable to A. ¢néscatus are included in what he 
calls canescens. 
13. Chelemys vestitus, Thos. 
9. 72. Beatriz, Nahuel Huapi. 
This single specimen is young, and therefore does not 
furnish any information as to the relationship of Ch. vestitus 
to the more northern Ch. macronyx of San Rafael, Mendoza. 
14. Geowus (gen. nov.) valdivianus, Phil. 
3. 92, 94,98,114; 9. 88,94, 95,96. Beatriz, Nahuel 
Tluapi. 800 m, 
