172 FIELD MUSEUM or NATURAL HISTORY ZOOLOGY, VOL. XI. 



Skulls of Murida. (About natural size.) 



i, Mus musculus; 2, Epimys norvegicus; 3, Peromyscus leucopus; 4, Oryzomys palustris: 5, Neo~ 

 tomaf. illinoiensis; 6, Evotomys gapperi; 7, Microtus pennsylvanicus; 8, Fiber zibethicus; 9, Synapto- 

 mys cooperi. 



