MURIDAS—ARVICOLINA—ARVICOLA AUSTERUS. 213 
usual. The skull is perhaps “remarkable for its elongation”; but it falls 
short of the specimen of haydeni, which measures 1.14, and only ‘exceeds 
average austerus by 0.06. ‘The supposed difference in the lengths of the 
nasals and the nasal branches of intermaxillary, owing to the shortness and 
truncation of the former, is no distinction, as we find it precisely matched in 
examples of unquestionable austerus (No. 4#s3'; No. @t53). The alleged 
differences in dentition are simply a little less deep infolding of the enamel 
loops on the back upper and front lower molars; so that the lateral triangles 
of the first-named tooth, instead of being closed up along the middle line of 
the tooth, intercommunicate; and the same is the case with the anterior 
exterior triangle of the last-named tooth. But this is merely a slight differ- 
ence in degree, not of kind. Among our specimens are some as closely 
approaching this pattern as others recede from it; and the differences in this 
respect among unquestionable austerus are quite as great as between austerus 
and “cinnamomea”. 
The following table gives the measurements of our series. 
TaBLE LIV.—Measurements of fifty-two specimens of ARVICOLA (PEDOMYS) AUSTERUS. 
Nose to— Tail to-- a 
as 
, aie 3 og 
E Date. Locality. Collector. s = 2 3 $ & z 
3 a/Siela/e|s os 
A Epil | red basi le (eeialfeet lt Gece ass 
=] mlals!|S|/a|)e2i] ols i 
Z all nll RO eee n 
2923 Spring, 1855 0.72) Alcoholic. 
a 
c R. Kennicott....|0, 41 
2995 iu |quilee dates 
g 
cd 
S 
pS eee 0. 72)....do. 
2931 BHU Ses ey be ec We se. soc Socoe Sosa espe eee! Ol Saee ne ar 0. 81)....do. 
2932 Sod. essacsa|pemeteit) mes sesacoocedscstocee| Sera Necaeoncenar 0. 71). ...do 
293% Sadi Opaaceee 0. 75)....do 
RO3L |. ...)-.--do.------ 0. 71)..-.do 
Pla | ss noc! Oiaes oss 0.75). - do 
2986" | 9 |°_.-do.---=-- 0.70 ....do. 
EG) ||| 2eel RRR ty eee 0.80, Dry. 
WC 9) ES ee eee see 0.75). ...do. 
1977 |...) Fall, 1856.... 0. 70). ...do. 
19738 2 | Summer,1856 \0..73}....do. 
2431 |... | Spring, 1855 |. 0. 74)... .do. 
2432 0 79). .--do 
2433 0. 73}.- do. 
2434 0.79) ..-.do 
2435 0. 78)....do 
2436 0. 81)....do 
2437 --|0. 79]....do. 
2438 \0. 80... do. 
2439 .| Fresh. 
2440 0. 78) Dry. 
2442 ..|....| Young;dry. 
2443 10. - Dry. 
