708 Laura Florence 



whose anterior l:)order lies approximatel.v on the anterior border of the 

 fourth segment. 



The structure of the female copulator3^ apparatus is much simpler than 

 that of the male. It is situated in the last three segments of the bod,y, 

 and the external indications of sex are the shape of the abdomen, two 

 triangular chitinous plates on the dorsal surface of segment 9 (which 

 ends in two pointed lobes), and the gonopods on the ventral surface of 

 segment 8. The gonopods (Plate LVIII, 11) are flat processes, triangular 

 in shape. Their median free border is somewhat strongly chitinized 

 and is set with a row of stout hairs. Anteriorly they are joined by a 

 fold of the integimient which projects caudad in two blunt points. As 

 has already been said, they appear to have arisen as an infolding of the 

 integument of the segment. The sexual orifice is on segment 8 under 

 the anterior border of the gonopods. It leads directh' into the vagina, 

 a thin-walled chitinous sac lying close to the ventral bodj^ wall and at 

 its anterior end passing into the uterus ventrad of its semicircular coO. 

 In Pediculus the walls of the vagina are covered with minute, outward- 

 pointing teeth. In Haematopinus no teeth could be seen on the vaginal 

 wall in gross preparations treated with potash and mounted in balsam. 



A plate of closely set muscle fibers originates in the anterior border of 

 segment 7 immediately posterior to the ventral abdominal muscle plate, 

 and is inserted in the anterior border of the gonopods. The contraction 

 of these muscles raises the gonopods and brings the sexual orifice and the 

 vagina into position for copulation. Muscle fibers originating in the 

 lateral wall of the vagina and in that of the uterus near its passage into 

 the vagina, are inserted in the sternite of segment 9, and bj' their contraction 

 draw the vagina and the uterus to their resting position. 



The histological structure of the ovarian tubes at different stages of 

 development has been thoroughly studied and described by Gross (1906: 

 352-364), and a brief resume of his work is 'here inserted. There is no 

 peritoneal wall surrounding the egg tubes, and the tunica propria (base- 

 ment membrane) is unusually well developed. In the terminal threads 

 of adult females the content consists of a homogeneous granular proto- 

 plasm which Gross regards as degenerated remains of the cells to be found 

 in younger stages. Landois (1864:16) had seen these cells also in the 

 terminal chamber of Phthirius, and he considered them as specific yolk- 

 forming elements and hence the terminal chamber of the one-egg tube 



