MUEID^. — CLXXXV. 319 



1036 b. Z. insignia Miller. Larger than Z. hudsomus, with 

 longer ears and paler, more fulvous coloration, tail with white tip ; 

 molars f;f. L. 10. T. 6. In deep woods, Penn. and N. Y. to 

 Nova Scotia. (Lat., distinguished.) 



Family CLXXXIV. GBOMYID^. (The Pouched 

 Gophers.) 



Cheek pouches large and distinct, opening outside of the mouth. 

 Molars |:|- ; incisors large and thick ; skull heavy ; temporal bones 

 enormously developed. Limbs about equal, the fore claws five in 

 number, very large ; tibia and fibula united. Body thick-set and 

 clumsy. Genera 2 ; many species ; all North American, and chiefly 

 inhabiting the central plains ; habits subterranean. Farther west 

 occur numerous species of Heteromyidm or Pocket Mice, smaller 

 than the Gophers, and with thin and papery skulls. 



a. Upper incisors, each with a large groove near the middle ; ears rudi- 

 mentarj'; fore claws enormous Geomys, 540. 



aa. Upper incisors not grooved ; ears distinct but very small ; claws 

 moderate Thomomys, 54L 



540. GEOMYS Rafinesque. (yrj, earth ; ^ivs, mouse.) 



1037. G. bursarius (Shaw). Pocket Gopher. Reddish 

 brown, with plumbeous tinge ; upper incisors with two grooves, the 

 larger near the middle line; tail and feet hairy. L. 11. T. 3. 

 Prairies, Wis., 111., and W. to S. Dak. and Neb. (Lat., pouched.) 



541. THOMOMYS Maximilian. (^w^oj, heap ; /xu?, mouse.) 



1038. T. talpoides (Richardson). Northern Pocket Go- 

 pher. Dusky plumbeous ; tail, feet, and breast mostly white •, 

 ears in a dusky area. L. 9^. T. 2^. Minn, to Plains and N. W. 

 (Lat., like a mole.) 



Family CLXXXV. MURID^. (The Mice.) 



Incisors | ; molars usually f if ; anteorbital foramen a vertical 

 slit, widening above and bounded externally by a broad plate of 

 the upper maxillary; coronoid and condyloid processes of lower 

 jaw well developed. Tibia and fibula united below. Genera 

 about 80. A large family, found in all parts of the globe, some 

 of the species {Mm) being cosmopolitan, having accompanied man 

 in all his migrations ; all are of small size, the muskrat being one 

 of the largest, and some are smaller than any other quadrupeds, 

 except the Shrews. 



a. Incisors broad, often broader than deep; molars rooted or rootless with fiat 

 crowns and re-entrant angles (body heavy, eyes small, snout blunt, legs 



