D. Keilin and GL H. F. Nutt all 
327 
the man, who was kept in bed, being clothed in flannelette pyjamas; a dozen 
nits were laid overnight upon the pubic hair. This and the other statements 
of this author but confirm what Nuttall ( loc. cit.) had already stated regard¬ 
ing the habits of corporis. 
Experiments with capitis. Head-lice, when placed inside the collar, wander 
to the head or are lost (Sikora, loc. cit.); when placed on the body, after at 
first showing a distinct tendency to wander to the head, the offspring of such 
lice grow less prone to wander headwards, whilst succeeding generations of 
head-lice adapt themselves completely to a life of parasitism on the body 
(Howlett, xi. 1917, p. 186). 
The foregoing evidence demonstrates that there are ample opportunities 
in nature for the intermingling of capitis and corporis , when they infest man, 
because they invade each other’s feeding grounds. 
REFERENCES. 
See Bibliography in Parasitolog //, x. 1-42, 582-586, and to be published. 
EXPLANATION OF PLATES XII—XVII. 
PLATE XII. 
Pediculus humanus race capitis $f, dorsum. Specimen 12, well pigmented, showing fragmented 
dorsal bands (see text, p. 290). 
PLATE XIII. 
Pediculus humanus race capitis f. Specimen 12 (the same as in PI. XII). Dorsal view of abdomen 
showing internal organs in cleared specimen. Two testes (t.) on the left side and one on the right; 
vesicula seminalis ( v.sem .) and ductus ejaculatorius ( d.ej.) obliquely placed; two large ova ( ov .) 
with opercula completely formed, one surmounted by the terminal portion of an ovarian tube 
(see text, p. 290). 
PLATE XIV. 
Pediculus humanus race corporis f. Specimen 13, cleared, viewed ventrally. Showing one testis 
on the insect’s right side (left in figure); vesicula seminalis and ductus ejaculatorius slightly 
pressed backward by six ova of which five are shown in the figure; a gonopodial invagination 
( gon.invag .), containing sensory hairs, is seen on the left side of the animal in the last segment 
(see text, p. 290). 
PLATE XV. 
Pediculus humanus race corporis f. Ventral aspect of the posterior part of the abdomen in three 
specimens: 
Fig. 1. Specimen 1. ventral plate separated in two portions. Gonopods almost symmetrical. 
» Basal plate (seen by transparency) very broad. 
Fig. 2. Specimen 2. ventral plate of left side of insect fused to $ ventral plate. Penis protruded 
with dilator. Posterior abdominal lobes of $ very small, rudimentary. The dorsal aspect 
of this specimen is shown in PI. XVII, fig. 6. 
Fig. 3. Specimen 3. Showing the bipartite ventral plate of $. Gonopods asymmetric. 
PLATE XVI. 
Fig. 1 . Pediculus humanus race corporis f. Specimen 5. £ ventral plate bipartite, 9 ventral plate 
and gonopods rendered salient by prolapsed vagina. Dilator twisted. 
Fig. 2. Pediculus humanus race capitis f. Specimen 12 (the same as in Pis. XII, XIII). £ ventral 
plate bipartite. $ ventral plate small, asymmetric. Gonopodial spot (gon.s.) on left side of 
insect. 
