2p8 Bulletin American Museum of Natural History. [Vol. XII, 



very much paler than O. ph(Eopus,\\ 7 \\\c\\ is described as nearly 

 agreeing in the color of the upper parts with the " vandyke- 

 brown " of Ridgway's ' Nomenclature of Colors,' and as " dirty- 

 buff " below ; while O. sanctcemart& agrees, above, quite nearly 

 with Ridgway's "tawny-olive," and is clear light-gray below. It 

 is also rather larger than O. phczopus, while O. p/i&opus obscurior is 

 described as still smaller and darker than O. phceopus. The fol- 

 lowing table shows the comparative measurements of these four 

 forms. 



Oryzomys mollipilosus, sp. nov. 



Type, No. 15323, ? ad., Valparaiso (alt. 4500 ft.), Santa Marta District, 

 May 10, 1899; Coll. II. H. Smith, " Mother of four young "collector's note 

 on label. 



Pelage soft and velvety, especially soft and downy on the ventral surface. 

 Color above, -yellowish gray-brown, strongly varied with black-tipped hairs, 

 tending to a blackish median dorsal area ; sides paler, gray-brown faintly 

 tinged with pale buff ; below clear uniform 'ashy gray, the basal half of the 

 hairs pale plumbeous ; -ears 'medium, blackish brown, almost naked ; tail dark 

 brown above, a little paler below, very finely scaled and nearly naked ; feet 

 flesh c61or. 



The young in first pelage are blackish brown, the hairs, more especially on 

 the sides, slightly tippedfwith pale yellowish-brown ; lower parts as in adult. 



Measurements. Type, total length, 233mm. ; tail, no,; hind foot, 25.5, with 

 claw, 28 ; ear (in dry skin), 14. A series of 3 adults measures as follows : Total 

 length, 33Q J (225-333) ; tail, iio (108-113) ; hind foot, 29 (27-30). 



Skull, total length, 30 ; basal length, 21.5 ; zygomatic width, 14 ; mastoid 

 width, 12 ; interorbital width, 5; length of nasals, 10 ; palatal length, 6 ; 

 length of palatal foramina, 3.8 ; length of upper toothrow, 4.3 ; length of 

 lower jaw, 18 ; height at condyle, 7 ; height at coronoid, 6.5 ; length of lower 

 toothrow, 4.5. Supraorbital bead well developed. 



Qryzomys mollipilosus is based; on four adults and three young, 



