VOL. XIV, PP. 153-155 AUGUST 9, 1901 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



ON THE MAINLAND FORMS OF THE EASTERN 



DEERMOUSE, PEROMYSCUS LEUCOPVX 



(RAFINESQUE). 



BY EDGAR A. MEARNS. 



Per&myscus leucopus was originally described by Rafinesque 

 from specimens taken during a journey through "the lower 

 parts of the Ohio, the Wabash, Green River, Barrens, Prairies, 

 and the states of Indiana, Illinois, &c." Kentucky is general 

 ly considered to be the type locality.* Specimens from Lex 

 ington, Kentucky, collected by the writer and assumed to be 

 typical, are found to agree with those from other parts of the 

 austral zone east of the Mississippi River; but, in the transi 

 tion zone, fairly well-marked geographical races occur in New 

 York and New England in the East, and in Minnesota in the 

 West. The range of the species does not extend beyond the 

 northern boundary of the transition zone, but meets with that 

 of Peromyscns camtdensis at the lower edge of the boreal zone. 

 In these forms, which may be recognized by the following de 

 scriptions, the under surfaces are wnite with more or less gray 



*In a letter "dated at. L<nn*rill<; Full* of Ohio, 20th July, 1818", pub 

 lished in the American Monthly Ma.ira/ine, Yol. Ill, September, 1818, p. 

 354, Rafinesque states respecting "(Juadru/H-dM": "I have discovered 

 and described 3 new species: 1. Mnwnlux lettropu*; '2. (Jerbillu* tft/lrati- 

 cnx; and, 3. Noctilio mi/staj', Rat'." 



30 BIOL. Soc. WASH. VOL. XIV, 1901. (153) 



