Ct. H. F. Nuttall 
395 
Since the mode of attachment, very close to the hair-base, and the 
orientation of the egg are similar in both species, it is certain that the 
process of oviposition must be similar in essential particulars (see 
Pedieulus, p. 118). The difference in the form of the cement mass that 
characterizes the eggs of Phthirus and Pedieulus (compare Figs. 5 and 6) 
is, in my opinion, doubtless attributable to the form of the gonopods 
in the respective females, this being a subject perhaps worthy of further 
study. As in Pedieulus, usually but one egg is laid upon a hair, about 
0-5 mm. from its base, but the eggs may be laid in succession on one 
hair, a dozen or more not uncommonly being present where the infesta¬ 
tion is heavy. 
Fig. 5. P/iiAiVws 7 )« 6 is egg on hair, lateral Fig. 6 . Pedieulus humanus (corporis) egg on 
aspect. hair, lateral aspect (ca. 1 mm. long; drawn 
to the same scale as Fig. 5). 
The number of eggs laid by a female is stated to be 10 by Giebel 
(1874, p. 26), 10-15 by Blanchard (1890, p. 443) and Railliet (1895, 
p. 828), but there is no mention of whence these figures are derived, 
although they are frequently quoted by various authors. Possibly the 
statements are based on guesswork. 
It is certain that Phthirus (as with Pedieulus) lays many more eggs 
than has hitherto been supposed. One female that I raised laid 26 eggs, 
and I suspect that she died prematurely. It would not surprise me to 
learn that a female may lay 50 eggs or more, but further experiments 
are required to determine what is the full complement. The maximum 
number of eggs laid by a female per day was three. 
