16 
JOURNAL OF MAMMALOGY 
CONCERNING LICE 
By G. F. Ferris 
Probably every collector of mammals has occasionally noticed the 
lice that usually come out to the ends of the hairs of a mammal within 
a few hours after it has been killed. But that very few mammal col- 
lectors have ever taken any particular interest in these parasites is 
sufficiently attested by the infrequency with which they are received 
by entomologists and the paucity of information concerning them. 
And, indeed, why should mammalogists take the time to collect a 
group of insects that have had little enough attraction even for entomolo- 
gists and that are usually spoken of in our entomological texts merely 
as “disgusting parasites,” illustrated by one or two crude figures and 
grudgingly accorded a page or two of passing mention? 
Yet these parasites are really of sufficient interest to merit something 
more than this scanty consideration. Rather than the apology for 
studying them, which prefaces a certain old book, there should be an 
apology for not studying them more. Aside from the importance 
accorded to the notorious “cooty” because of its disease-transmitting 
proclivities there are other factors that may justly entitle them to 
some share of our attention. The special interest of the lice in general 
lies in the fact that they may be made to contribute some small addi- 
tion to the mass of evidence upon which our theories of evolution are 
based. 
No one can study these insects for any length of time without being 
struck by certain peculiarities in the distribution of the various groups 
and even of the various species. Here are a few of these peculiarities, 
chosen more or less at random. What is the explanation of them? 
The various species of Microtus and related genera, both in Europe 
and North America, have upon them the same species of louse. There 
are upon the various species of Citellus and related genera in western 
North America two species of lice that are apparently identical with 
two species which occur upon at least some of the Siberian species of 
Citellus. There is upon the llama in South America a very peculiar 
louse that appears to be identical with one which was originally de- 
scribed from the camel. There occurs upon the California sea lion a 
louse that is found also upon another Otariid in the Antarctic region, 
although these two mammal species are separated by at least the width 
of the tropics. There is upon the harbor seal of the California coast 
a louse that occurs also upon the various species of Phoca in the Atlan- 
