a subfamily of rodents of the family Cricetidae; some zoologists place the rodents in a separate family. The average body length is 10–12 cm (sometimes as long as 36 cm); the tail is half as long as the body (sometimes shorter). The upper-part of the body is usually solid gray or brown. The cheek teeth of most species are rootless and ever-growing. Only a few extant species and most fossil forms have cheek teeth with roots. The chewing surface of the teeth is prismatic.

There are more than 40 genera of microtines, more than half of which are extinct. The USSR has 12 extant genera, with 43 species. In the northern hemisphere they inhabit the continents and many islands south to northern Africa. The animals also dwell in northern India, Japan, the Kuril and Komandorskie islands, and northern Mexico. They live in the mountains to elevations having no vegetation. In the north, microtines are even found in coastal regions. The greatest diversity of species and the largest number of individuals are found in the open terrain of the temperate zone. Most microtines settle in colonies. They are active year-round, feeding primarily on the above-ground parts of plants. Some species hoard food. The animals reproduce throughout the warm periods of the year, and some species reproduce even in the winter. The number of microtines may vary sharply from year to year. Most species are serious pests of agricultural crops and are natural carriers of the organisms causing tularemia, leptospirosis, and other diseases. The skins of large species, for example, muskrats, are used in the manufacture of fur goods.

I. M. GROMOV