19 
Giebel credits this species to Moufet, citing the Tbeatrum Insector. 
(1G34, 286), while Piaget states that it is cited by Moufet on the author- 
ity of Albertus (rv., C. 205), which would carry its recognition back to 
the thirteenth century. Linnaeus described it under the name of Ped- 
iculus suis, which name has been most commonly followed, but Nitzsch 
revived the name of urius and this name has been followed by Giebel 
and Piaget. Along with other parasites it received frequent mention 
by both early and modern writers. Denny speaks of it as rare in Eng- 
land, but common in Ireland. He says (Monog. Anop. Brit., p. 35) : 
"This species is found in great numbers on swine, but it does not ap- 
pear so generally spread as might be expected from the dirty habits of 
the animals. It most frequently oecurs on those fresh imported from 
the sister isle. It was many months before I could obtain a single ex- 
ample. I had applied to both farmers and pig butchers, neither of 
whom seemed to approve of the idea which I had conceived, that of 
their pigs being lousy, but referred me to those of the Emerald Isle as 
being sure to gratify my wishes (forgetting, I suspect, that the Irish 
pigs come to this market to meet English buyers). I accordingly vis- 
ited a colony just arrived, where I most certainly met with a ready sup- 
ply; but here they were confined almost entirely to lean animals, and 
wherever I found a pig fat or healthy no game were to be seen." 
Most stockbreeders have probably seen instances of its abundance, 
and from the frequent mention of it in the agricultural papers, it would 
seem to be quite commou throughout the country, and while, perhaps, 
less generally distributed than the ox-louse, to multiply some times so 
as to cause much more apparent damage to its host. The fact that 
they are more commonly found on poor or runty animals should not be 
taken as evidence that they have a preference for such animals, but 
rather that the animals upon which they have multiplied rapidly have, 
in consequence, become emaciated and unhealthy. That they do not in- 
crease more rapidly and become a much greater nuisance may be in part 
because the majority of hogs are sold and slaughtered at a compar- 
atively early age, and with each one slaughtered must perish the para- 
sites which have been supported by it, unless, perchance, an occasional 
one escape the scalding trough and succeed in finding another host. 
Of the vast number of hogs shipped to market and slaughtered at the 
great packinghouses, none can bequeath the insects they have nurtured 
to their followers. The amount of injury and the consequent need of 
precautionary measures are, therefore, much less for this species than 
for many others. 
This is one of the largest species of the family, full grown individuals 
measuring a fourth of an inch or more in length. It is of a gray color, 
with the margins of the head and thorax and most of the abdomen 
dark. The head is quite long, the sides nearly parallel, with strong 
eminences just back of the antennae, which are set on the sides of the 
head, midway from rostrum to occiput : the legs are lighter with dark 
