560 The American Naturalist. [June, 
A Geomys lutescens, kept in confinement by Dr. Merriam, could run 
backward as rapidly and easily as forward. The well-known peculiar- 
ity of the external genitalia of the male, which are so hidden and modi- - 
fied that the sexes are determined with difficulty, is doubtless connected 
with this habit, the parts being protected from injury when the animal is 
moving backward. Another fact learned by Dr. Merriam from the 
captive Geomys is that the tail functions as an organ of touch. It is 
rather large and fleshy, and is apparently endowed with special tactile 
sensibility, and is evidently of great value in warning the animals of 
the presence of an enemy in the rear when they are traveling back- 
ward in their dark tunnels. 
Dr. Merriam has divided these animals into several genera, but the 
characters regarded as definitive seem to be hardly sufficient for that 
purpose. They appear to us to be more properly sections of a —_ 
genus. 
A Monograph of the Bats of North America.’—This work 
is one of a series of papers intended to illustrate the collections belong- 
ing to the United States National Museum. It is, in reality, a revision 
of a monograph published in 1864 by the same author, with such 
additions as haye been necessitated by the study of new material. The 
old descriptions have been elaborated, the new standards of compari- 
sons adopted, and many newly observed anatomical details included in 
the introduction. 
The region covered by the monograph includes North America, ex- 
tending to the southern limit of the United States. 
Thirty-eight plates, of skillfully executed drawings, give the details 
of the external characters, of the osteology and of the dentition. The 
work is authoritative in this branch of N. American mammalogy, and 
the student of this subject will find it a sine qua non. 
. 
RECENT BOOKS AND PAMPHLETS. 
ABBOTT, W, J. I.—The Ossiferous Fissures in the Valley of the Shode, near 
Ightham, Kent. Extr. Quart. Journ. Geol. Soc., 1894. From the author. 
ALLEN, J. A.—Descriptions of Ten New North American Mammals, and 
Remarks on Others, Extr. Bull. Am. Mus. Nat. Hist., Nov., 1894. From the 
author. ; 
; ê Bulletin of the U. S. Natl. Mus., No. 43. The Bats of North America. By 
Harrison Allen, M. D., Washington, 1893. 
