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JAN., 1912. MamMALS, VENEZUELA AND COLOMBIA — OsGoop. 51 
Characters. Somewhat similar to T. laniger and T. monochromos, 
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 vertebre 147; hind foot 26.5. Average of 10 adult topotypes: 
261 (240-275); 120 (108-126); 141.6 (132-152); 25.8 (25-27). 3 
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 toothrow 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 
