D. Keilin and G. H. F. Nuttall 
295 
organs: viewed dorsally by transparency, the specimen shows structures 
resembling a rudimentary basal plate and vesica penis; one left testis is 
well developed, young ovules are present. 
SPECIMEN 32, f. Not illustrated. 
Resembles Specimen 31 in some respects. 
Dorsal bands complete, broad. Legs: pair I as in 
c?, pair III as in $. Ventral plate with one antero¬ 
lateral extension forming a separate plate, the 
other united by a very narrow neck (recalling 
Specimen 28 shown in Text-figure 10 c). Posterior 
abdominal lobes truncated, asymmetric, the left 
lobe being much reduced. Abdominal muscles: 
dorsally as in <?, ventrally as in $ but the second 
set of muscles, incomplete. Internal organs: one 
large testis filled with spermatozoa, young ovarial 
tubes, their relations obscurely visible. A sub- 
gonopodial prolapse is present; it consists of basal 
plate, dilator, penis and vesica penis, all distorted 
and reduced; this complex doubtless corresponds 
to the rudimentary $ genitalia which are con¬ 
tained inside the body of Specimen 31. 
Description of Bacot’s 123 Hermaphrodites: Material (c). 
This material contained males, females, and 123 hermaphrodites, derived 
from various crosses between capitis and corporis (see Table on p. 315) as 
follows: 
Cross I. Corporis $ x capitis ?: the 3 generations F l9 F 2 , F 3 contained 
no hermaphrodites, the males predominated over the females. 
Cross II. Capitis $ x corporis 2: the 3 generations F x , F 2 , F 3 contained 
1 hermaphrodite (Specimen 33), the proportion of the sexes in this case being 
also abnormal, there being more males than females. 
SPECIMEN 33. Of § type , very pale. Legs: pair I as in <J, pair III as 
in $. $ genitalia asymmetric, with protruded penis; on the ventral side in 
the median line there is a large invaginated chitinous mass with sensory 
hairs, this representing the vagina and gonopods of $. Muscles invisible. 
Internal organs: a distorted vesicula seminalis; testes and ovules present, 
but it is difficult to determine their number and to define their contours. 
Cross III. Capitis $ x corporis $: yielded but one generation, F l9 with 
very few specimens and no hermaphrodites. 
Cross IV. Capitis $ x corporis $: yielded but one generation, F 1 , com¬ 
prising males and females in equal numbers (43: 43) and 5 hermaphrodites. 
Text-fig. 12. Pediculushumanus 
Specimen 31. Abdomen in 
dorsal aspect, showing frag¬ 
mented dorsal bands and £ 
genitalia (b.pl.= basal plate), 
the latter seen by transpar¬ 
ency. (K. & N. del.) 
