244 University of California Publications in Zoology [Vol. 21 



While fairly intermediate in characters of size and color between 

 parvula and M. f. sierrae, fortirostris departs decidedly from both in 

 the structure of the rostrum of skull, which is notably short and heavy. 

 In comparison with parvula, the skull of fortirostris of similar age 

 shows heavier incisors, deeper as well as broader rostrum, and wider 

 frontal region. 



LITERATURE CITED 



Bailey, V. 



1915. Eevision of the pocket gophers of the Genus ihomomys. U. S. Dept. 

 Agric, Bur. Biol. Surv., N. Amer. Fauna, 39, 136 pp., 8 pis., 10 figs, 

 in text. 



Grinnell, J. 



1918. Six new mammals from the Mohave Desert and Inyo regions of Cali- 

 fornia. Univ. Calif. Publ. Zool., 17, pp. 423-430. 



Howell, A. H. 



1915. Eevision of the American marmots. U. S. Dept. Agric, Bur. Biol. 

 Surv., N. Amer. Fauna, 37, 80 pp., 15 pis., 3 figs, in text. 



Transmitted August 20, 1921. 



