Tue Hoa Louse 653 
transverse split; the chitin on each side of the median rupture is stretched 
back so that the opening resembles a triangle. The first pair of legs is 
next withdrawn, and these, pushing down the skin, help in the final freeing 
of the head and the mouth parts. These now occupy their normal position, 
and the second and then the third pair of legs are withdrawn, pushing the 
insect forward and freeing it from the old skin, which remains anchored 
to the surface upon which the insect has emerged. The process took 
place when a louse had been put on the arm to feed and was watched 
through a binocular. From the first rupture of the old skin until the 
complete emergence of the insect, thirty minutes elapsed; Sikora (1915: 
525-526) describes the process in Pediculus vestimenti as lasting but five 
minutes. No description of the act has been found in the literature of 
the hog louse, and the slowness in the case observed may have been due 
to the unnatural environment of the insect; moreover, death followed 
within an hour of molting. 
THE ADULT LICE 
The male and the female are recognized by their difference in size, the 
shape of the abdomen, and the structure of the two posterior abdominal 
segments. Both are without pigmented eyes, but the projections on the 
sides of the head have a lateral, slightly convex, refractive surface sugges- 
tive of a lens. While the thorax of the female is somewhat shorter and 
broader than that of the male, the legs of the sexes are identical, showing 
no modifications for clasping in relation to copulation. No constant 
variations in pigmentation have been observed. 
THE MALE 
The abdomen of the male is considerably shorter than that of the female, 
so that, although it measures the same or even slightly less in its widest 
region, 1t appears considerably broader. The tergites of segments 1 and 
2 are small, but clearly defined. Hairs are present in each abdominal 
segment in a transverse row. Posteriorly the abdomen is rounded; the 
terminal segment curves dorsad and anterior, bringing the rectal and 
sexual orifices into a dorsal position (Plate LVIII, 8). On the ventral 
surface there is a strongly chitinized plate of characteristic shape extending 
from the transverse median line of segment 7 through segment 8 to seg- 
ment 9, its posterior edge being visible from the dorsal aspect of the 
