RECENT LITERATURE. 
The American Naturalist for February contains a number of arti- 
cles of interest to zoologists. Recent Studies of the Vertebrate 
Head by H. W. Norris. Also, Some of the Causes and Results 
of Polygamy among the Pinnipedia by C. C. Nutting; the best and 
most striking example of true polygamy among mammals is shown 
to be the northern fur seal ( Cal/orhinus ursinus) of which the male 
weighs from three to nearly six times as much as the female. The 
species exemplified are walrus (Odobenus rosmarus), hooded seal 
( Chrystophora cristata), bearded seal ( Erignathus barbatus), sea 
elephant ( J/acrorhinus angustirostris), Stellar’s sea lion ( Zumato- 
pias stelleri), and northern fur seal ( Callorhinus ursinus), in the 
order of their sexual disparity in size. ‘‘ The writer has endeavored 
- to account for the following peculiarities met with among the Pinni- 
pedia: 
1st. The relation between great sexual disparity in size and po- 
lygamy. 
2d. The manner in which polygamy may have originated. 
3d. The origin and effect of excessive pugnacity. 
4th. The origin and advantage of great sexual disparity. 
5th. The origin and advantage of the ability to endure long- 
protracted fasts.”’ W. E. B. 
Description of Two New Species of Rodents from Mexico. By 
Henry L. Warp. American Naturalist, xxv, p. 158. The new 
species are Spermophilus sonoriensis, which is “apparently quite 
similar to Dr. Merriam’s recently described S. cryptospilotus,’’ and 
Neotoma torquata, which may be distinquished from all others of 
the genus by ‘“‘a well defined collar, 20 mm. in width” upon the 
breast. The collar is light Vandyke brown, washed with black. 
Ww. E. B. 
Notes on a Collection of Mammals. Srom Costa Rica. By J. A. 
ALLEN. Bull. Am. Mus. Nat. Hist., iii, 2, 203-218. A report 
upon a collection of thirty-eight species with annotations and yield- 
ing the following which are described as new: Blarina costaricensis, 
Hesperomys ( Vesperimus) cherrii, Hesperomys ( Vesperimus? ) nu- 
dipes and Hesperomys ( Oryzomys) alfarot. Wot Be 
On a Collection of Mammals from Southern Texas and North- 
eastern Mexico. By J. A. ALLEN. Bull. Am. Mus. Nat. Hist., 
