204 Bulletin American Museum of Natural History. [Vol. 



wi tli black, with a tendency to a, blackish median dorsal area; below uniform 

 rusty brown, the rusty tips of the hairs often quite concealing the grayish under 

 color ; ears blackish, nearly naked ; tail dusky, unicolor, entirely naked, the. 

 scanty very short hairs in no degree concealing the annulations ; feet dusky 

 (hind feet blackish), thinly haired. 



Measurements. Type, total length, 230 mm.; tail vertebrae, 102 ; hind foot, 

 27, without claws, 24 5 ; ear (in dry skin), 14. Four adult specimens (3 males, 

 and I female) measure as follows : Total length, 222 (207-230) ; tail vertebrae,, 

 97 (94-102) ; hind foot, 26.5 (25-27). 



Skull, total length, 30; basal length, 23; zygomatic width, 16, mastoid 

 "width, 13 ; interorbital width, 6.5 ; length of nasals, 7 ; length of palatal foram- 

 ina, 4.6 ; length of upper toothrow, 4.8 ; length of lower jaw (condyle to tip of 

 incisors), 17,5, height of lower jaw (coronoid to angle), 7.5. 



Akodon columbianus differs from its nearest geographical ally^ 

 A. venezuelensis, by its much darker color, and very long, wholly 

 naked tail, and by the unusual shortness of the rostral portion of 

 the skull, and the corresponding shortness of the palatal foram- 

 ina, which also terminate posteriorly considerably in advance 

 of the first molar. While apparently as dark in color as A. bogo- 

 tensis, it differs from that species in its larger size, very long tail, 

 and in important cranial characters, the proportions of the skull, 

 being quite different, with the usual resulting differences in 

 details. 



'This species is based on 4 specimens, 3 of which were taken at 

 Ma.nzanares (altitude 3000 feet), September 6, 1899, and the 

 other at Minca (aJfitude 2000 feet), July 17, 1899. They are all. 

 adult, and very uniform in, coloration. 



Oryzomys maculiyenter, sp. nov. 



Type, No. 15306, ,$ ad., Sierra,, El Libanq (alt. 6000 ft.), Santa Matta Dis- 

 trict, Colombia, May 17, 1899; Col J: n - H - Smith. ,_ 



r Pelage full, long,, and soft. Color above tawny rufous varied with black 

 tipped hairs, Brighter and clearer tawny on the sides ; top of head darker and- 

 less tawny than the back; nose and sides of face to the eyes gray ; beneath pure 

 whiten-in adtilts the hairs are;cle.ar white to the base all over the ventral surface, 

 ^hich is sharply dej^n^d against the sides ; forearm and manus pure white to 

 above the elbow ; hind limbs externally like the sides of the body, less rufous on 

 the inner face ; hind feet gray with a tinge, of fulvous, especially proximally ; 

 ears rather large, brown, nearly naked on both surfaces except on the anterior 

 bkse externally^; tail naked, bicolor, brown above, flesh-color .below. 



Measurements. Type, total length, 335,ram.; tail, 170 ; hind foot, 32 (with- 

 out claws/; 29^; ear (in dry skin), 19, Twenty-eight -adults, 18 males an dMo- 



