MALLOPHAGA FROM MAMMALS 55 



VI 



NORTH AMERICAN MALLOPHAGA FROM MAMMALS 



The list of the Mallophaga recorded from American mammals (in- 

 cluding the records of this paper) comprises twenty-seven species, of 

 which nine occur upon domesticated hosts. 



These twenty-seven species are distributed among five genera, of 

 which four — Heterodoxus, Trimenopon, Gliricola and Gyropus — are rep- 

 resented by a single species each. The other species all belong to the 

 genus Trichodectes, which, as a matter of fact, includes four-fifths of all 

 the mammal-infesting Mallophaga. (In a recent paper, "Ectoparasites 

 of Mammals," published in the American Naturalist, vol. 48, pp. 257-279, 

 1914, the senior author discusses in some detail the interesting conditions 

 of the generic distribution of Mallophaga among the mammals.) 



The species of the genus Trichodectes find their hosts among such 

 extremely diverse mammals — diverse as to habits as well as phylogeny — 

 as gophers, beavers, pocket-rats, skunks, badgers, porcupines, cats, dogs, 

 horses, cattle, goats, sheep, deer, and even monkeys. Yet in spite of this 

 wide range of hosts, the genus is remarkably homogeneous, there being 

 but little breaking up of the species into particular groups associated with 

 particular groups of phyletically or habit-related hosts. 



In this respect the mammal-infesting Mallophaga present a striking 

 and interesting contrast with the other group of permanent ectoparasites 

 of mammals, that is, the Anoplura. Among these latter there is an ex- 

 tremely pronounced breaking up into groups — groups fairly characterized 

 as distinct genera, sub-families and even families — the species of each of 

 which are characteristic of certain restricted groups of hosts. It is, in- 

 deed, a rule almost without exception that any single Anopluran genus is 

 confined to a single host order, or even to a single host family. 



It is probable that a closer study of the mammalian Mallophaga will 

 warrant some breaking-up of the large genus Trichodectes into three or 

 four lesser genera ; one or two students have made a beginning of such 

 an analysis. But the possibilities of such a breaking-up are limited ; the 

 plain truth is, that the differentiation and heterogeneous specialization of 

 the Anoplura is far and away beyond that of the Mallophaga. 



However, such a condition is but the one to be expected. It should 



