110 JESSE LE ROY CONEL 



rior ends, the convolutions become quite pronounced and regular. 

 There is but one convolution in each somite; the ducts bend lat- 

 erad at the interseptal lines and mediad between these Unes. 

 The convolutions continue to the posterior end of the body 

 cavity, but in the last five or six somites they diminish in extent. 

 The greater size of the male duct is caused principally by the 

 fact that its lumen is larger than that of the female. The walls 

 of the male duct, however, are somewhat coarser than those of 

 the female. 



No such convolutions occur in the ducts of the females. The 

 ducts bend laterad more or less slightly at the interseptal lines, 

 but there is no suggestion of the convoluted condition of the 

 male ducts. 



At their posterior ends, the ducts of both males and females 

 have the same gross structure and appearance. The two ducts 

 leave the peritoneal cavity at its posterior end, approach each 

 other and continue a short distance (5 to 10 mm.) along the dor- 

 sal surface of the genital chamber, then converge sharply. At 

 the point of convergence the ducts bend ventrad and laterad, 

 and become abruptly narrowed to very small tubes (figs. 47 and 

 48). The latter continue posteriorly, bend sharply ventrad at 

 the posterior end of the cloaca, and open in this region of the 

 cloaca on a papillary enlargement on a prominent ridge which 

 extends along the dorsal wall of the genital chamber and cloaca. 

 The two openings lie alongside, but one is usually slightly pos- 

 terior to the other. 



The ducts of young males (fig. 49) are not convoluted at any 

 place, and resemble in appearance and gross structure those of 

 adult females. 



Histology. Figures 50 and 51 are camera lucida drawings of 

 transverse sections of a male and female duct, respectively, 

 taken from the mid-region of the body cavity. The section of 

 the male duct was selected where there is the smallest possible 

 effect on the internal structure because of convolution. As 

 the figures show, the ducts consist of an inner epithelium and an 

 outer envelope of connective tissue. 



