1891.] Polygamy Among the Pinnipedia. 103 
SOME OF THE CAUSES AND RESULTS OF POLYG- 
AMY AMONG THE PINNIPEDIA’ 
BY..C.:C. NULTTING, 
oe geen years ago the writer was much struck by the great 
sexual differences met with among the Gallinæ, and had 
noted the fact that there was a relation between sexual disparity 
in size and polygamy. 
During the last summer an opportunity was afforded to care- 
fully observe one species of the Pinnipedia, and these observations 
led to a perusal of all the available literature for facts concerning 
the relation between sexual disparity and polygamy in this order. 
The results of this study had already been outlined for a paper 
to be read before the Iowa Academy of Sciences, when an article 
appeared in the November number of the Natura cist entitled 
“Probable Causes of Polygamy Among Birds,” by Samuel N. 
Rhoads. 
The above facts are mentioned to show that the conclusions as 
to the cause of polygamy among birds on the one hand, and Pin- 
nipedia on the other, were the result of independent investigations, 
and hence will serve to strengthen each other in some important 
particulars. _ 
True polygamy is something of a rarity among the Mammalia. 
It must not be confounded with mere promiscuous sexual inter- 
course, suchas is often met with among the Herbivora. The 
term polygamy, in its strict sense, can properly apply only to those 
species in which a single male habitually copulates with several 
females, and jealously and persistently defends them from the 
approach of other males. 
The most typical examples of this state of affairs are met with 
among the Pinnipedia, and ultra polygamy is exemplified by the 
northern fur seal (Callorhinus ursinus). 
Two striking facts at once arrest the attention of even the most 
cursory observer of this species : 
Ist, The astonishing extent to which polygamy is carried. 
1 Paper read before the Iowa Academy of Sciences, Jan. rst, 1899. 
