MURID&—ARVICOLIN4—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 (7iparius and townsendi) 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, Bachman. 
Townsend’s Meadow Mouse. 
Arvicola townsendii, BACHMAN, Jour. Acad. Nat. Sci. Phila. viii, 1839, 60; Townsend’s Narr. 1839, 315.— 
WAGNER, Wiegmann’s Archiv, 1843, (ii), 53.—Aupb. & Bacu. Q. N. A. ili, 1853, 209, pl. 
exliv, fig. 1.—Barrp, M. N. A. 1857, 527.—NewBerry, P. R. R. Rep. vi, 1857, Zool., 61.— 
Coorer & Suck ey, Nat. Hist. Wash. Terr. 1860, 129. 
Arvicola (Myonomes) townsendi, Cours, Proce. Acad. Nat. Sci. Phila. 1874, 190. 
Draenosis.—Arvicola statura inter majores, longitudine trunct 5-6 polt., 
capitis sesquipoll., caude 24-poll., pedis 1-poll., maniis fere $-poll.; auriculis 
