D. Keilin and Gr. H. F. Nuttall 283 
end of the dilator frequently protrudes from the body. The abdomen bears 
a ventral plate and is rounded posteriorly. See Text-figs. 2, 3 1 . 
FEMALE (Text-fig. 4). The female possesses two ovaries, each consisting 
of five ovarial tubes which terminate in oviducts ( ovid .) that unite and enter 
the uterus (ut.) dorsally. The uterus communicates ventrally with the vagina 
and laterally with the paired accessory glands ( acc.gl .). The vaginal orifice 
lies ventrally in the form of a transverse slit situated beneath two gonopods 
which curve towards each other in the median line. Anterior to the gonopods 
lies the ventral plate. The abdomen ends in two posterior lobes. See Text- 
fig. 5 1 . 
Text-fig. 5. Pediculus humanus race capitis $ (Lot 237, v. supra). Normal specimen. (A) Posterior 
part of abdomen in ventral aspect: gonopods ( gon .), ventral plate ( v.pl .), posterior lobes 
(p.l.). (B) Normal variation in form of ventral plate. (N. del.) 
Secondary somatic characters. 
Size. The d is usually smaller than the $, but the character is inconstant. 
Leg I. In the d, the first leg differs from the others in being more powerful 
and possessing a large thumb whereby the female’s third leg can be firmly 
grasped during copulation. Leg I in the female does not differ from the others. 
Leg III. This leg is characterized, in the $ only, by a spur situate ventrally 
near the base of the femur 2 . 
Dorsal bands (Text-fig. 3). Normally, these are only present in the d- 
They consist of a series of paired transverse bands occurring dorsally upon 
the abdominal segments and are especially evident in well-pigmented speci¬ 
mens. 
Abdominal muscles.. In the d, the dorsal longitudinal muscles form an 
uninterrupted series extending from the thorax to the last segment, and the 
ventral longitudinal muscles occur in four successive rows starting at the 
1 For descriptions and illustrations of the normal d and $ genitalia and interscgmental 
abdominal muscles, see Nuttall, Parasitolot/i/, ix. 293-21)(>, where their functions are explained. 
2 Text-fig. 23 will serve to illustrate the characters of d lug t and $ leg III respectively. 
