MAMMALS OF NORTHERN COLOMBIA—HERSHKOVITZ 27 
Measurements of the holotype (in millimeters).—Head and body, 207; 
tail, 200; hind foot, 55; ear, 27; condylobasal length, 46.5; zygomatic 
breadth, 29.5; length of nasals, 16.8; supraorbital constriction, 16.5; 
postorbital width, 17.7; width of braincase, 22.5; alveolar length of 
molar row, 9.0. 
Coloration of the paratopotypes (3 males, 6 females).—Throughout 
this dusky series, the pattern of blackish agouti with little contrast on 
the shoulder regions is consistent. ‘Terminal portions of tails black in 
all specimens; in one specimen, middle orangeous portion of upper sur- 
face heavily mixed with black and limited to an area of about 2 inches 
in length; on undersurface, this tail is nearly entirely black except at 
base. In the series, the undersides of the tails may appear bicolor in 
middle portions with the outer band either black or reddish, or tricolor 
with an orangeous, a black, and a mixed yellow and black band. 
Underparts' of body entirely reddish or with narrow patches of white 
along mid line. 
This is a well-marked population distinguishable from zuliae by 
the redder (mars orange) sides and underparts, the greater amount of 
black on dorsum, and by slightly smaller average size. It is difficult 
to assign this series to any of the other named forms. It may eventu- 
ally prove to be part of the gradient between zulzae and maracaibensis. 
GuAMALITO (4 males, 3 females): Both geographically and in its 
characters, this series occupies a position between the topotypes of 
variabilis and zuliae. It consists of highly variable individuals with 
one specimen agreeing well with some of the typical forms of peryae, 
another with maracaibensis, though it has large patches of white on 
the belly. In general, however, the series is most like the topotypes 
of tarrae. Dorsally as dark as the Tarra specimens, but with shoulder 
regions more contrastingly reddish; ventrally with an approximately 
equal distribution of white and reddish, the former color persisting 
over a greater area than latter on throat, neck, chest, midventral line 
and around genitalia. Tails with more black than variabilis, less 
than in the Tarra series. The specimen, a subadult, agreeing with 
perijae, is orangeous with an even ticking of black spread lightly over 
the dorsum. The squirrels were taken at altitudes ranging from 600 
to 1,000 meters above sea level. 
Remarks.—The range of iarrae lies between those of peryae and 
zuliae, and parallels them in extending from east to west across the 
cordillera. Apparently, the distributional pattern of each of these 
forms follows closely the pattern of the fluvial systems in the Sierra. 
The system is pursued from near the base of the mountains to the 
divide, thence across to a connecting system on the other side. 
Specimens examined.—Seventeen. Rio Tarra, 10 (U.S.N.M.); 
Guamalito, 7 (U.S.N.M.). 
