Pygerethmus

(fat-tailed jerboa), a genus of rodents of the family Dipodidae. The body measures as much as 12.5 cm in length, and the tail, as much as 13.5 cm. The tail is often greatly thickened from fatty deposits. The coloring of the upper parts is sandy ocher. The genus’ two species inhabit semideserts and clay deserts from the lower Emba River to the Zaisan Depression. They are rare in all areas of distribution.