456 On neio Mammals from Ecuador and Venezuela. 



type, by Mr. J, Grabara Kerr, enables me to make a better 

 comparison between the two than was formerly possible. 

 The true pusilla is much smaller, has a narrower and more 

 rounded skull, while its dorsal colour does not show the 

 peculiar waviness which additional material proves to be 

 quite constant in the Merida form. The same is true of 

 Lagoa Santa specimens representing Burmeister's Orymceomys 

 ay ill's. 



Marmosa dryas^ sp. n. 



Size of M. marica. Fur long, as in that species. General 

 colour dull rufous fawn, darker and more uniform than in 

 that species. Centre of face but little lighter. Under surface 

 dull rufous throughout, except for a white patch on the chest; 

 no line of demarcation on sides. Cheeks and chin rather 

 paler rufous, not white. Hands and feet whitish above. 

 Tail very short-haired as usual, brown above, rather paler 

 below. 



Skull with a much narrower and more sharply pointed 

 muzzle than in M. marica. Zygomata not so boldly diver- 

 gent as in that animal, especially anteriorly, where, in fact, 

 their profile, as viewed from above, is almost concave. Inter- 

 orbital region smooth, its edges diverging backwards, not 

 ridged. Palate longer and narrower than in the allied species, 

 the two rows of teeth more nearly parallel. 



Dimensions of the type (an adult skin, said to be that of a 

 male) : — 



Head and body 97 millim. ; tail 147 ; hind foot (wet) 18'4 ; 

 ear 16. 



Skull : basal length 24*8 ; greatest breadth 15 ; nasals 

 ll'7x3'.S; interorbital breadth 5"2 ; palate, length 15, 

 breadth between outer corners of m.^ 8'1 ; combined length of 

 W5.1-3 4-9. 



Hah. Culata, Merida, 4000 m. Coll. S. Briceno. 



Type : B. M. no. 98. 5. 15. 2. Killed Dec. 14, 1896. 



Some time ago Mr. Briceno sent home a single specimen 

 of this form, but I could not then be sure that it was not a 

 mere spasmodic colour-variation of M. marica^ but now four 

 additional examples identical with the first have been obtained, 

 and show conclusively that it is really a different species to 

 the common Merida form. It may be readily distinguished 

 by its darker general colour, its dull rufous instead of 

 yellowish-white belly, and its narrower and more pointed 

 skull. 



