44 Field Museum of Natural History — Zoology, Vol. XL 



a2. Tail not thickly haired; cheeks with large external pouch open- 

 ing outside of mouth; front of incisors 

 deeply grooved; claws on fore feet very 

 long. 



J^' lfff//j Family GEOMYID^. 



~^ \J(J Pocket Gophers, p. 239. 



It. 



B. Not more than 3 well developed grinding teeth on side of jaw; tail 

 closely haired, or in some species nearly or quite naked, 

 bi. Hind feet ordinary, not greatly elongated. 



Family MURID^. Rats and Mice, p. 171. 



b2. Hind feet much elongated; tail very long; size small (in one 

 species a very small premolar is present in 

 addition to the three well developed molars). 



Family ZAPODID.^. Jumping Mice, p. 246. 



SECTION 2. Upper front teeth (incisors) 4; two large incisors and 

 two very small ones directly behind them; 

 ears and hind legs noticeably long. 



}^f/ Family LEPORID.S. Hares and Rabbits, p. 259. 



