from North-western Patagonia, 203 
greyish slaty band, dividing the subdued buffy area of the 
- back from the greyish white of the belly, while in sugfusus 
the same lateral region is buffy brownish in continuation with 
the back. ars with a fairly well-marked greyish-white spot 
at their notch and on the base of the metentote. Under 
surface clear greyish white, quite as in suffusus. Feet white. 
Tail definitely bicolor, blackish above, whitish below, as in 
sufjusus. 
Skull as in suffusus. 
Dimensions of the type :— 
Head and body 97 mm. ; tail 68; hind foot 23°5 ; ear 17. 
Skull: greatest length 29 ; condylo-incisive length 25:8 ; 
zygomatic breadth 14'2 ; interorbital breadth 4°8 ; breadth 
of brain-case 13; palatal foramina 6°6 ; upper molar series 41. 
fab, as above. 
Type. Adult male. B.M. no. 18.12. 2.22. Original 
number 204. Collected 2nd May, 1918. 
This form, by its more subdued colour as compared with 
true suffusus, forms a step towards the following subspecies. 
9, Abrothrix suffusus merens, subsp. n. 
G62 10,15. TG, Feds 69) 80, 8b, 82,83, 84, 895 90 
Oo 97, 99, 107, 107, 112,115, 116; 2 65, 67, 63, 69, 74, 
86, 104, 106, 110, 117. Beatriz, Nahuel Huapi. 800 m. 
Much darker than true sug/usus or the previous subspecies, 
the back dark brown almost without buffy, and the belly— 
which is practically white in suffusus and modestior— deep 
dull grey,” very much as in the Chilian dongipil’s. Ears 
almost without greyish patches at their bases. Hands and 
feet grey, near “pale neutral grey.” Tail averaging a little 
shorter than in the other forms, and less markedly bicolor, 
blackish above, greyish below. 
Skull as in suffusus. 
Dimensions of the type :— 
Head and body 110 mm.; tail 72; hind foot 22:5; 
ear 16. 
Skull: greatest length 29; condylo-incisive length 26 ; 
zygomatic breadth 14; interorbital breadth 5; breadth of 
brain-case 12°43; palatal foraina 6°6; upper molar series 4:2. 
Hab. as above. 
Type. Old female. B.M. no. 19.1.1. 22. Original 
number 104. Collected 25th February, 1918. 
This form of Abrothrix, from the lake-region of Nahuel 
Huapi, is, so far as colour is concerned, much more distinct 
from A. suffusus than is that of Maiten, and I have hesitated 
