The tail is scantily haired and about the same color as the back, except that in some specimens the tip is white. These marsupials could with equal justification be called shrewlike or ratlike in general form. The head is elongate, the eyes are very small, and the ears are rounded and project above the pelage. The tail tapers gradually and is nonprehensile. On the other four digits have well-developed, curved claws.
Females have four mammae but no pouch.
These marsupials occur in the alpine forest and meadow zone of the Andes, at altitudes of about 1,500-4,000 meters. They prefer cool, wet areas covered by thick vegetation. They are nocturnal and terrestrial and move from one favored area to another by means of runways through the surface vegetation. These authorities also reported that C. fuliginosus and C. inca may bound at high speed but are not saltatorial. They are primarily terrestrial, but they are agile climbers and use their tail as a prop as they move up a vertical surface.