172 The Philippine Jow^nal of Science 1919 
The cattle louse {Hxmatopinus eurysternus Nitzsch)/ though 
present, can scarcely be said to be abundant in the Philippines. 
Its habits are practically the same as those of the carabao 
louse, which it resembles. It may be distinguished from the 
former by the more strongly scalloped outline of its abdomen, 
the greater width of its thorax, and the longer tarsal claws. 
Closely related to the above-mentioned species is the hog 
louse {Hsematopinus urius Nitzsch) found throughout these 
Islands. It may be distinguished by its long slender legs with 
acutely curved tarsal claws mottled with dark brown, and by 
the black, strongly chitinous, lobed, lateral margins of the ab- 
dominal segments, the last *of which is truncated and double- 
notched. The hog louse is slightly smaller than the cattle louse 
and more glabrous and transparent than either it or the ca- 
rabao louse. 
The goat louse (Hsematophms stenopsis Burm.) is fairly com- 
mon on goats wherever they are found and was undoubtedly 
introduced with these animals just as the other species of the 
genus were brought in with their respective hosts. It is less 
than half as long as the cattle louse and very slender and is 
usually found gorged with blood. 
Related to the goat louse is the rat louse {Hsematopinus spin- 
ulosus Denny), which is common on these rodents when they 
are congregated in considerable numbers in bodegas and else- 
where. This insect is much smaller than the goat louse, of a 
uniform pale straw yellow, except when full of blood, and has 
a very much rounded face, with projects little beyond the 
antennee. 
Kellogg ^ has set forth the view, in discussing the biting lice 
(Mallophaga) , that the same species of these parasites occurring 
on different species of birds argues the existence of a common 
ancestor for the latter. With equal reason we might assume 
that in other parasites, as the sucking lice, the closeness of their 
relationship might be further proof of the common ancestry of 
species now as widely separated as Homo sapiens L. and the 
other members of the Primates. 
The monkey louse {Peclicinus eurygaster Gerv,), which is 
found on all monkeys in these Islands, bears a very close resem- 
blance to the species of the genus Pediculus; in fact, the former 
differs only in having eight abdominal segments and five-seg- 
mented antennse, while the latter has nine abdominal segments 
* Op. cit., p. 45. 
'American Insects. New York (1908), 117. 
