The Hog Louse 707 



organ; by Mtiller (1915), vyho alao showerl a number of figures; and by 

 Peacock (1916). Nuttall (1917 a : 312) described the copulatory apparatus. 



The essential reproductive organs of the female are the paired ovaries 

 and their oviducts, with the colleterial glands. The remaining parts 

 are the uterus and the vagina (Plate LXV, 1). In the hog louse neither 

 spermatheca nor bursa copulatrix is present. 



The ovaries are clustered, consisting of five egg tubes on each side, 

 and this number seems to be constant in the Siphunculata according to 

 the different workers in the group, but the number of egg chambers in 

 each tube differs in the various species. Each egg tube consists of a 

 terminal filament, a terminal chaml^er or germarium, and as a rule two 

 egg chambers or vitellaria although three are sometimes seen. The 

 fine terminal filaments of each ovary of a pair unite, and pass as a single 

 filament above the mid-intestine into the fat cells and their tracheoles. 

 Graber (1872:1.59) alone, among the earlier workers, thought that three 

 terminal filaments, or vessels as they were then called, passed from each 

 egg tube; but, as Gross (1906:350) suggests, he probably confused tracheae 

 with terminal threads. The ovaries lie in the abdominal cavity on each 

 side -of the mid-intestine, and in the region of the si.xth abdominal segment 

 they fuse to form a short common oviduct on either "side. They pass 

 into the uterus at the anterior border of the seventh segment after receiving 

 the colleterial glands, which are large, trilobed glands with convoluted 

 edges. Their anterior lobes, pointing cephalad, lie along each side of 

 the mid-intestine under the lateral borders of the ventral abdominal 

 muscle plate, and extend to midway between the posterior and anterior 

 borders of segment 4; the posterior lobes are shorter, and, pointing caudad, 

 extend just within the anterior border of the eighth segment; the lateral 

 lobes surround the oviducts and the mid-intestine near the anterior 

 border of segment 7. 



The uterus is surrounded by a stout muscular wall which, as Landois 

 (1865 a: 51) first pointed out, is made up of circular as well as longitudinal 

 fibers. After receiving the oviducts it passes caudad through segment 

 7 into segment 8, then bends back along itself just into segment 7, where 

 it again turns caudad describing a semicircle, so that the point of its passage 

 into the short, thin-walled vagina lies on its own spiral. The meaning of 

 its length and musculature is revealed in examining specimens ha\'ing a 

 mature egg in the uterus. It is then a long, straight, antl wide tube, 



