inew Species of Marmosa. 521 
Skull: condylo-basal length 30; zygomatic breadth 17°3 ; 
nasals 12°2 x 3°2; interorbital breadth 4°4; breadth of brain- 
ease 11; palatal length 15°7; maxillary tooth-series 10:8; 
three anterior molariform teeth 4:4. 
Hab. Northern Chaco of Paraguay. Type from Mision, 
west of Concepcion. 
Type. Old female with much worn teeth. B.M. no. 
20. 12. 18. 34. Original number 15. Collected 29th July, 
1920, and presented by the Marquis de Wavrin. Two 
specimens. 
Of the three species of this group that occur in the Paraguay 
region, A. marmota, the largest, occurs in Paraguay proper 
—type-locality Tapoua, specimens seen from Sapucay and 
Asuncion,—while the smaller M. citella occurs at Goya, 
Corrientes, to the south of Paraguay. Now the present 
species, agreeing in size with the southern one, occurs to the 
north of marmota, in the Chaco Boreal. 
All three are alike in colour, but may be readily distin- 
guished by their respective sizes and the development of their 
bullee. 
This makes the third new species discovered by the 
~ Marquis de Wavrin, whose little collection from the Chaco 
has proved of remarkable interest *, 
Marmosa numetra, sp. n. 
A large species resembling MZ. chapmani of Trinidad. 
Size and colour almost exactly as in M. chapmani, though 
the under surface is much more strongly suffused with buffy 
—“light ochraceous buff”; back near “cinnamon.” Ears 
decidedly smaller than in chapmani. Feet large and heavy. 
Tail proportionally rather short, with about a half or three- 
quarters of an inch furry like the body. The remainder pale 
brown, sometimes spotted with whitish, even more completely 
naked than usual, decidedly less hairy than in chapmani, the 
hairs quite minute, and imperceptible without a strong lens. 
Skull as in chapman?, with strong supraorbital ridges, not 
broadly overhanging the orbits. Canines of normal shape, 
not broadened antero-posteriorly at base, as they are in the 
available specimens of chapmani, 
Dimensions of the type (measured in flesh) :— 
Head and body 166 mm.; tail 205; hind foot 24; 
ear 25. 
Skull: greatest Iength 41°7; zygomatic breadth 22-2; 
nasals 19x 5:1; interorbital breadth 7°3; breadth across 
* Cf. Oryzomys wavrini and Akodon toba, supra, pp. 177-178. 
