G. H. F. Nuttall 
393 
on the approach of a male. Once, when the stocking was removed, a 
pair were found to have apparently been disturbed in the act, for the 
male was found with the forepart of his body beneath the female. 
The latter was clinging to two hairs and feeding in the usual way, but 
her abdomen was raised, whilst the male rested freely upon the skin 
between the hairs, with the end of his abdomen turned upward. Three 
days later. Dr Keilin witnessed the act and made a rough sketch of the 
pair in copula. From this sketch, with the aid of specimens, I have 
attempted to represent what was observed in the accompanying illus¬ 
tration (Fig. 3). The male was almost hidden by the superposed body 
Fig. 3. Phthirus puhis, showing the position of the sexes when in copulation, the female 
being uppermost. The male grasps the hair behind the female and, contrary to 
P. humanus, does not seize her legs. 
of the female. The posterior end of the male was bent upward but the 
copulatory organs could not be distinguished, therefore no attempt is 
made to represent them in the figure. A¥hilst the female grasped two 
parallel hairs, the male grasped but one of them, he grasped a third 
hair with his opposite leg-pair. In neither insect did the first leg-pair 
appear to perform any duty. The act was completed in ten minutes. 
Whilst a description of the genitalia of Phthirus is deferred for con¬ 
sideration in the section on anatomy, I would note the salient feature 
wherein copulation differs in this species and Pediculus (see Parasitology, 
IX. 293). The Phthirus male does not grasp the female’s legs, his first 
leg-pair are weak instead of strong and they appear to perform no 
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