190 PROCEEDINGS OF THE ACADEMY OP 



Arvicola modesta, Bd., op. cit. 535, (Rocky Mts.) (Very young.) 

 Arvicola rufidorsum^ Bel., op. cit. 526. (Mass.) (Reddish specimen.) 

 Arvicola ireioeri, Bd., op. cit. 525 (Muskeget, Mass. ; bleached insular 

 race). 



la. Arvicola (riparius var. ?) borealis, Rich. ? 



Syn. f Arvicola borealis, Rich., Zool. Journ. 1828, 517 ; F. B. A. i. 1829, 

 127. Also of Aud. and Bach., and of Baird. 



Eab. Northwestern America. 



Obs. This and the two succeeding species are presented provi- 

 sionally. 



2. Arvicola (Myonomes) townsendii, Bach. 



Syn. Arvicola iownsendii, Bach., J. A. N. S. P., viii. 1839, 63, and of 

 subsequent writers. 



Hah. Oregon and Washington Territories. 



3. Arvicola (Myonomes) xanthognatlius, Leach. 



Syn. Arvicola xanthognatlia, Leach, Zool. Misc. i. 1814, 60, pi. 26. 

 Rich., F. B. A. i. 1829, 122. Aud. and Bach., Q. K A. iii. 1853, 

 67, pi. 125. Bd., M. N. A. 1857, 552. Dall, Alaska and its Re- 

 sources, 1870, 577. Whether of Sabine ? but certainly not of any 

 author treating of United States species. 



Hab. British America. 



Obs. In its typical condition the animal is unmistakable in its 

 immense size (up to 8 inches long) and chestnut cheeks. There 

 remain, liowever, some points to be elaborated before the relation- 

 ship of the several forms of BIyonomes can be considered estab- 

 blished. 



Subgenus Chilotus, Baird. 



Syn. Chilotus, Baird, 1857. Type, A. oregoni. Bach. 



4. Arvicola (Chilotus) oregonus, Bach. 



Syn. Arvicola orcgoni, Bach., J. A. N. S. P., viii. 1839, 60. Aud. and 

 Bach., Q. N. A. iii. 1858, 232, pi. clxvii. f. 3. Bd., M. N. A., 1857, 

 537. 



Hab. Oregon. 



Subgenus Pedomys, Baird. 



Syn. Pedomys, Bd., M. N. A. 851, 517. Type, A. austerus, LeC. 



5. Arvicola (Pedomys) austerus, Le C. 



Syn. Arvicola austertis, Le C, P. A. N. S. P. vi. 1853, 405. (Wiscon- 

 sin.) 

 Arvicola {Pedomys) austerus, Bd., M. N. A. 1857, 532, pi. liv. (Wis- 

 consin and Missouri to Louisiana.) 



