Description of Meadow Mouse. 599 
molar, and three internal and at least two external closed triangles 
on its front lower molar—and consequently is a Myonomes, closely 
related to our common eastern meadow mouse, Arvicola (Myonomes) 
riparius. The “upland” species has but one external closed trian- 
gle on the back upper molar, lacks the “spur” of the preceding 
tooth, and has but two internal and one external closed triangles on 
the front lower molar—in other words is a Pedomys, nearly related 
to the prairie meadow mouse of the Mississippi Valley, Arvicola 
(Pedomys) austerus. For purposes of critical comparison, therefore, 
the remaining sub-genera of Arvicola may be summarily dismissed. 
The sub-genus Pedomys, according to Coues, the latest monographer 
of the group, contains but the single species, austerus. He also 
placed in this sub-genus, and in fact as only sub-specifically separa- 
ble from austerus, a very different mouse (namely, his Arvicola aus- 
terus curtatus) which is not, a Pedomys at all, but, as I have recently 
shown, belongs to the sub-genus Chilotus. This leaves austerus as 
the only species with which Mr. Bailey’s “upland” mouse may be 
compared. The principal difference is in size, the new form being 
\ 2 
male Arvicola (Pedom J 2 Í 
ys) minor Merriam. 1 and 2, skull from about and below 
+ Upper molar series, X5; 4, lower molar series, <5. 
— that in the case of the mice the ranges of the two are not 
— to overlap. In my series of considerably more than a hun- 
Specimens of qusterus proper I do not find a single adult indi- 
2245 
x2; 3 
