MAMMALS OF NORTHERN COLOMBIA—HERSHKOVITZ 31 
from widely separated points at altitudes ranging between 2,000 
and 3,000 meters along the eastern Andes of Colombia and Ecuador. 
They form a fairly homogeneous group and nowhere can such sharp 
differences be found between any two of them as between two such 
neighboring coastal forms as griseogena and maracaibensis. Never- 
theless, all along the lower borders of the range of these dusky high- 
land squirrels, forms have been described which connect them with the 
larger, brightly colored coastal, or lowland, animals. It has been 
shown that meridensis, by way of the series from the Paéramo de 
Tamé, grades into the lowland maracaibensis through the races 
zuliae and tarrae. In Ecuador the highland carchensis shows gradation 
into the coastal versicolor through the races séderstrémi and imbaburae 
which occupy successively lower altitudinal levels. At the northern 
extreme of the Eastern Andes it has been noted that the longer- 
haired paler and more uniformly agouti representatives of perijae 
resemble individuals of meridensis. The former subspecies includes 
also individuals which lead to the lowland maracaibensis on one side 
and splendidus on the other. 
Specimens examined.—Eleven. Montes de Escorial, Mérida, 2,500 
meters, 2 (U.S.N.M.); Montes de la Culata, Mérida, 2,500 meters, 
1 (U.S.N.M.); Montes de Hechizera, 2,000 meters, 1 (U.S.N.M.); 
Paramo de Escorial, 3,000 meters, 1 (U.S.N.M.); Montes de Chama, 
Mérida, 1,600-1,700 meters, 2 (U.S.N.M.); Montes de la Sierra, 
Mérida, 2,000 meters, 1 (U.S.N.M); Péramo de Tama, 8,000 feet, 
3 (C.N.H.M.). 
GEOGRAPHIC VARIATION 
A complete picture of the geographic variation within the species 
cannot be given here. The following discussion is based primarily 
upon the squirrels collected by the author in a small corner of the range 
in northern Colombia and some complementary material collected 
by others in adjacent regions. Of necessity, some references are 
made to more distantly located specimens. The localities from 
which squirrels are at hand represent almost completely all the major 
ecological subdivisions frequented by squirrels in the area under 
consideration (see map, fig. 1). The only important ecological 
community not satisfactorily represented is that of the highest alti- 
tudinal levels inhabited by squirrels in the Sierra Nevada de Santa 
Marta. A brief description of each of the collecting localities is 
given in the gazetteer (p. 40). 
Commencing with the squirrels taken in the lowlands of the Rio 
Magdalena, we find members of each of three markedly differentiated 
subspecies occupying adjoining ranges and subjected to the same 
environmental conditions. The type localities of these three races 
have been established at points so near to each other that an energetic 
