New Species of Aplodontia. 



32? 



animal was disposed of by Cones in his Monograph of the genus. 

 ''Professor Peters," writes Dr. Cones, "described specimens 

 from California as constituting a new variety, to which he ap- 

 plied the name Haplodon leporinus var. Calif ornicus. I have 

 seen no specimens from that region, nor is the material at present 

 available sufficient to enable us to come to final conclusions re- 

 specting the normal rate of susceptibility to individual variation. 

 The few specimens, however, indicate that the rate is at least as 

 high ms that which has been established for various mammals 

 more or less closely allied ; and, should such prove really the 

 case, there would be no impropriety in considering var. califor- 

 nicus as strictly synonymous." (Monographs of North Ameri- 

 can Kodentia, 1877, p. 598.) This statement of Cones contains 

 one error of fact (for Peters had but one specimen — not speci- 

 mens), and its final assumption w T as based, doubtless, on a very 

 hasty examination of Peters's description. 



CRANIAL DIFFERENCES RESULTING FROM SEX AND AGE. 



In placing the adults of A. major side by side, the most notice- 

 able sexual difference is found in the suture which separates the 

 frontal bones from the premaxillaries and nasals. This suture 

 is open in the females and closed in the males. 



Fig. 1. Aplodontia major $ ad. (JSo. 2107 Mus. C. H. M.) showing 

 persistent fronto-premaxillary suture. Natural size. 



