The general coloration of S. forresti is grayish brown. In this species there is an inconspicuous narrow, whitish, lateral line, beneath which is a dark line from the shoulders to the hips. The underparts are pale reddish brown, the flanks are reddish, the chest and throat are white, and the tail is like the back but darker near the tip. Some zoologists think that these squirrels represent a connecting link between the pouched chipmunks and the true squirrels. They have small cheek pouches and a slightly lengthened snout.
Females have three pairs of mammae.
In S. davidianus the soles of the feet are densely haired, but in S. forresti the soles of the hind feet are almost naked. These squirrels inhabit rocky, shrub-clad mountain cliffs and avoid dense tree growth. Their habits apparently are like those of chipmunks, but they do not hibernate. Although they are able to climb trees, they seldom do, preferring to travel about rocky terrain, which they do with great agility. They make their homes in deep crevices and between rocks.