South- American MuridEe. 497 



brown. This colour extends over the whole of the head and 

 upper surface. Belly paler, the tips of the hairs dirty buff. 

 Ears short, blackish. Limbs dark coloured, hands and feet 

 smoky grey above ; claws rather long and slender. Tail about 

 two thirds of the length of the head and body, well covered with 

 hair ; black above, pale greyish below, the two colours not 

 sharply defined. 



Skull almost precisely similar to that of A. lasiuruSy as 

 figured by Winge *j although smaller. Upper profile evenly 

 convex. Nasals short and narrow. Interorbital region 

 smooth, its edges with well-defined ridges, which, however, 

 practically end where they meet the parietal bone. Inter- 

 parietal small and narrow. Palatal foramina open, with 

 rounded margins, extending back to the level of the antero- 

 internal notch of m^. Proportions of teeth about as in 

 A. lasiurus. 



Dimensions of the type (measured in spirit before skin- 

 ning) :— 



Head and body 98 millim., tail 64, hind foot 19, ear 13. 



Skull: basilar length 22"6; greatest breadth 14*9; nasals 

 8-3 t X 3-1 ; interorbital breadth 4-7 ; interparietal 2*3 x 7 ; 

 palate length from henselion 12'7; diastema 8*2; palatal 

 foramina 6"1 X 2'1 ; lengtli of upper molar series 4'5. 



Hah. Source, Marajo Island. 



Type. Male. B.M. No. 97. 4. 1. 3. 



II. The Species of the Genus Nectomys. 



Kectomys has a very different range to that of Holochilus ; 

 it extends northwards to Surinam on tiie east, and to Colombia, 

 Ecuador, and Peru on the west, and on the other hand is 

 only found southwards to Rio Grande do Sul, no species 

 having been as yet recorded from Uruguay or the Pampas 

 districts. 



The best known species is N. squamipes, Bts. (incl. aqua' 

 ticus, Lund), which seems to be spread over most of Brazil, and 

 from which I cannot separate either Surinam or Rio Grande 

 do Sul specimens. How far it ranges inland is doubtful, but 

 it is possible that " Ilesperomys rattus, Pelzeln " |, from Mara- 

 bitanas. Upper Rio Negro (which, though the type is too 

 young for certain determination, is clearly a Nectomys) , may 

 prove to belong to the common species. N. squamipes has 



* PL ii. fig. 11. 

 t Imperfect anteriorly. 



X Natt. Bras. Saug. ii., S.B. zool.-bot. Ges. Wien, xxxiii. Beiheft, 

 p. 73 (1883). 



