MURIDM— ARVICOLIKZE— ARVICOLA TOWNSENDI. 185 



to be not Pedomys, and there is consequently little danger in referring them 

 to riparius. If this determination be correct, the southward known range of 

 the .species is considerably extended. 



In concluding this discussion of Arvicola riparius, we have a word of 

 personal explanation. We sincerely trust that the manner in which we have 

 conducted the investigation will be sufficient to relieve us of any possible 

 charge of arbitrary or even injudicious rejection of many species that stood 

 upon high authority. We began the study with a mind as free from precon- 

 ceived ideas as possible ; and, if we had any bias of judgment, it was a pre- 

 judice in favor of the validity of the species that were recognized in 1857. 

 At one stage of our study, we had already been forced to give up the idea 

 that there were more than two species {riparius and totvnsendi) of this 

 section in the United States, but still believed in the possibility of defining 

 several geographical varieties that might be properly recognized by name. 

 Final examination, however, of the subject, with facilities, in the immense 

 and unparalleled amount of material, never before enjoyed by any naturalist, 

 has satisfied us that it is impossible to diagnosticate even permanent varie- 

 ties or geographical races. Even "breweri", which seemed a clear case of 

 an insular variety, has proved to graduate into the average form ; and we do 

 not conceive that any good would result from retaining this, or any other of 

 the names that have been proposed, in the system. We have no alternative, 

 then, but to throw all the names together as indistinguishable synonyms of 

 riparius. In 1857, many names, all doubtless supposed, by their several 

 proposers, to indicate valid species, were either formally or virtually sup- 

 pressed ; and a further reduction of eight is simply an advance, pari passu, 

 with the increase of our knowledge on the subject. We trust that we have 

 proven the position we take, and that we have seen the last of nominal species 

 based upon the endless variations of Arvicola riparius. 



ARVICOLA (MYONOMES) TOWNSENDI, Bach man. 



Townsend's Meadow Mouse. 



Arvkola townsendii, Bachman, Jour. Acad. Nat. Sci. Pbila. viii, 1839, 60; Townsend's Narr. 1839, 315. — 

 Wagner, Wiegmann's Archiv, 1843, (ii), 53.— Aud. & Bach. Q. N. A. iii, 1853, 209, pi. 

 cxliv, fig. 1.— Baihd, M. N. A. 1857, 527.— Newberry, P. R. R. Rep. vi, 1857, Zoo]., 61.— 

 Cooper & Suckley, Nat. Hist. Wash. Terr. 1860, 129. 



Arvicola (Myonomes) townsendi, CorjES, Proc. Acad. Nat. Sci. Phila. 1874, 190. 



Diagnosis. — Arvicola statu? d inter majores, longitudine trunci 5-6 poll., 

 capitis sesquipoll., caudre 2^-poll., pedis 1-poll., mantis fere ^-poll.; auriculis 



