MiUer.] 460 [Jan. i*. 
The first broken hymen was noted on March 28 (Peromyscus 
leucopus canadensis, Elizabethtown, N. Y.). Of seven Evotomys 
gapperi taken at ElizabetlitOAvn, April 4-13, only two had broken 
hymens. In one of these the uterus contained three small 
embryos; in the other it. was filled with a whitish fluid. Those 
with whole hymens had empty uteri. Of the fourteen Peromyscus 
(four P. leucopus, ten P. 1. canadensis) taken at the same time 
and place, the majority had broken hymens, but unfortunately I 
did not note the exact number. 
A female Peromyscus leucopus taken at Weston, Mass., May 2, 
showed no trace of the hymen. The uterus contained three very 
small embryos. 
Of two female Peromyscus leucopus taken at West Dedham, 
Mass., May 8, one, an adult, had the hymen perfect and com- 
pletely closing the vagina. The uterus of this individual con- 
tained five embryos. The other, a young one in the plumbeous 
coat, had a perfect hymen and empty uterus. A female of the 
same species taken at Provincetown, Mass., May 22, showed 
exactly the same conditions as the adult just mentioned. Two 
females of Microtus pennsylvanicus were taken on the same day. 
In one of these the hymen was pierced by a small opening ; in 
the other it was complete, though retaining the scar of a recent 
break. The uterus of the first contained five small embryos ; 
that of the second was empty, but retained the marks of recent 
placental attachments. The mammae were active. There can be 
no doubt that in this case the mouse had very recently given 
birth to young, and that the hymen had since formed so as 
completely to close the vagina. 
These facts present the gross conditions as I have observed 
them in many of the smaller American Muridae and also in the 
European 3Ius st/lraticus, Evotomys glareolus^ and MicrotUH 
agrestis. 
So long ago as 1812 Legallois noticed tliat in the guinea pig 
and house mouse the vaginal orifice is usually closed. He speaks 
of ". . . une disposition singuli^re du vagin de la femelle. Cette 
disposition consiste en ce que Porifice ext^rieur en est coll6 et 
compl^tement ferm6. II faut que la male le d^coUe pom- que la 
copulation ait lieu : il se recolle ensuite au bout de trois jours ; il 
se recolle meme apr6s I'accouchement. . . . Du reste, cet heureux 
J 
