520 Mr. O. Thomas on 
expanded in front of the anterior point of the frontals, 
rather more so than in c?tel/a. Bullee fairly large, propor- 
tionately about as in e/tella, much larger than in emilie. 
Premolars evenly increasing in length backwards. 
Dimensions of no. 1048 (taken on the skin) :— 
Head and body 75 mm. ; tail 89; hind foot (wet) 11°3; . 
ear (wet) 15:5. 
Skull: greatest length 23:5; condylo-basal length 23-1 ; 
zygomatic breadth 13°5 ; nasals 10 x 2°1; interorbital breadth 
3°7; breadth of brain-case 10°1; palatal length 12-2; max- 
illary tooth-series 8°8 ; combined length of three anterior 
molariform teeth 4°1. 
Hab. San Luis, Argentina. Original specimens from 
Alto Pencoso, just west of San Luis city. 
Type. Adult male. B.M. no. 21. 4. 21. 8. Original num- 
ber 1048. Collected February 1914, and presented by 
Dr. Carlos Bruch. ‘I'wo specimens. 
This beautiful little “ comadreja” is widely different from 
any species hitherto known by its small size and pale colour, 
the latter indicating a more or less desert habitat. In bulk 
it is about equal to the smallest described species of MZarmosa 
—WM. emilie of Para,—but is only related to the group of 
species to which JM. elegans, marmota, and citella belong, 
from any of which it is readily distinguished by its small 
size, and notably its tiny feet. 
In working out M/Z. bruchi I have re-examined some speci- 
mens of the same group from the Northern Chaco of Paraguay, 
presented to the British Museum by the Marquis de Wavrin. 
The Marmosa now also proves to be new, in spite of its 
superficial resemblance to Jf. marmota and citella. It may 
be called } 
Marmosa verax, sp. 0. 
Like WV. citella, but with smaller bulle and shorter feet. 
Size just about as in WM. citella, consequently smaller than 
in M. marmota, the species of Paraguay east of the main 
river. Coloration quite as in those two species. Hind feet 
proportionally small, shorter than in evtella. 
Skull as in eztella, with the same slightly expanded nasals 
and unridged supraorbital edges ; but the bulle are markedly 
smaller, a diagonal measurement taken on a line running 
from the basion to the middle of the zygoma 2°5 mm., while 
it is from 3 to 3:2 mm. in citella. 
Dimensions of the type:— 
Head and body 125 mm.; tail 130; hind foot 14; 
ear 23. 
