1895.] Zoology. 759 
the St. Petersburg Museum. At first glance I was impressed by the 
strong resemblance of this animal to our members of the pallidus 
group; and a detailed comparison of the skulls, teeth, and external 
characters of the two serves only to confirm this view. They agree in 
the small flattened skull with squarish, depressed braincase and short 
nasals; the pattern of the molar teeth (not only the number and rela- 
tions of the triangles, but also the distant spacing of the loops poste- 
riorly and the appearance of immaturity of the posterior molar in both 
jaws) ; the structure of the hinder part of the palate; the short wooly 
hind feet ; the short tail ; and even the softness of the polage and pale 
coloration. In Mr. Miller’s specimen the audital bulle and occipital 
region are broken off, but on comparing these parts in the Amercian 
members of the pallidus group with Buchner’s figures of Eremiomys 
[—Lagurus] lagurus*, they are found to be essentially identical. The 
posterior part of the braincase is not only flattened, depressed and very 
broad, but the audital and mastoid bulle are unusually large and the 
latter project decidedly behind the plane of the occiput. From the 
close agreement in the above mentioned essential characters, and the 
absence of important differences, I unhesitatingly refer the American 
Microtines described under the names Arvicola curtatus, pauperrimus 
and pallidus, to the Eurasian Lagurus. The principal differences are 
that L. lagurus has the tail even shorter than our species, and the ear 
decidedly smaller. There is also a more or less clearly defined dark 
streak down the middle of the back that is not present in the American 
forms. 
Lagurus is commonly accorded full generic rank, but I am unable 
to appreciate more than subgeneric weight in the characters that dis- 
tinguish it from Microtus. Why it has been called a lemning instead 
of a vole I am not able to understand. 
It is gratifying to add another group to the Microtines of Circum- 
polar distribution and at the same time lesson the number restricted to 
a single continent. Lagurus is a Boreal group, finding its southern 
limit in the Transition Zone-—C. Harr MERRIAM. 
The Introitus Vaginz of certain Muridz.—A series of ob- 
servations made by Mr. G. I. Miller, during the winter and spring 
months of 1890 and 1891, prove conclusively that in many of the 
smaller American Muride and also in the European Mus sylvaticus, 
Evotomys glareolus and Microtus agrestis the vaginal orifice, during 
pregnancy, lactation and the period of sexual inactivity, is tightly 
_ 4 Przewalski’s Reise nach Central-Asien, Siiugethiere, liefr. 3, 1889, pl. XIII. 
