JAN., 1912. MAMMALS, VENEZUELA AND COLOMBIA OSGOOD. 51 



Characters. Somewhat similar to T. laniger and T. monochromes, 

 but larger with relatively small ears and a very long white-tipped tail. 

 Pelage very long, soft, and lusterless; upper parts tawny olive rather 

 heavily mixed with blackish, occasionally with a heavy concentration 

 of blackish on middle of back; ears thinly haired or nearly naked dis- 

 tally, a tuft of soft black or blackish hairs at their anterior bases and 

 extending backward over the anterior third of the ear conch; sides and 

 face wood brown to tawny olive; a narrow and indistinct blackish eye 

 ring; under parts cinnamon overlying slate color; fore feet silvery gray; 

 forearm blackish; hind feet whitish drab, tarsal joints blackish brown, 

 digits white ; tail blackish above and below except a well-marked white 

 tip. 



Skull with ample braincase, the parietals slightly bulging; rostrum 

 rather narrow and slightly depressed; front border of zygomatic plate 

 somewhat receding; supraorbital border rounded anteriorly, very slightly 

 angled posteriorly; palatine slits nearly or quite reaching plane of first 

 molars; mesopterygoid fossa extending anteriorly to plane of middle of 

 last molar; upper incisors with relatively little recurvature. 



Measurements. Type: Total length 273; head and body 126; 

 tail vertebrae 147; hind foot 26.5. Average of 10 adult topotypes: 

 261 (240-275); 120 (108-126); 141.6 (132-152); 25.8 (25-27). 



Skull of type: Greatest length 30.5; basilar length 24.5; zygomatic 

 breadth 16.3; interorbital constriction 4.7; length of nasals 10.8; width 

 of nasals 1.3-3.7; postpalatal length 11.3; diastema 8.3; palatine slits 

 6.1 x 2.5; maxillary too throw 5.1. 



Remarks. Although well characterized otherwise, this species is 

 to be recognized most readily by its long white-tipped tail. The amount 

 of apical white varies from a mere pencil to nearly two inches and is 

 totally absent in only one of a series of twenty-nine specimens. These 

 were found associated with Oryzomys meridensis in the depths of the 

 forests on the upper slopes of the paramo living among the innumerable 

 galleries naturally formed under moss-covered roots, logs, and debris. 



Rhipidomys fulviventer Thomas. Buff-bellied Vesper Rat. 



Two specimens, Paramo de Tama, Venezuela. 



The under parts of these specimens are quite sharply distinguished 

 from the upper parts and although there is slightly more buffy suffusion 

 across the middle of the belly than elsewhere, the general color from the 

 chin to the vent is creamy white rather than fulvous. Still it cannot 

 be called pure white and it may be within the variation of this species 

 which is described as "fulvous or even buff, the line of demarcation 



