The Collaborative International Dictionary of English v.0.48:

Microsthene \Mi"cro*sthene\ (m[imac]"kr[-o]*sth[=e]n), n.
   [Micro- + Gr. sqe`nos might, strength.] (Zool.)
   One of a group of mammals having a small size as a typical
   characteristic. It includes the lower orders, as the
   Insectivora, Cheiroptera, Rodentia, and Edentata.
   [1913 Webster]