REPRODUCTIVE ORGANS. 265 



of the first two pairs of abdominal appendages. In both 

 sexes the gonads are three lobed, and communicate with the 

 exterior by paired ducts. 



The testes consist of two anterior lobes lying beneath and 

 in front of the heart, and of a median lobe extending back- 

 wards. Each lobe consists of many tubules within which 

 the spermatozoa develop. From the junction of each of the 

 anterior lobes with the median lobe, a genital duct or vas 

 deferens is given off. This has a long coiled course, is in 

 part glandular, and ends in a short muscular portion opening 

 on the last thoracic limb. The spermatozoa are at first disc- 

 like cells, they give off on all sides long pointed processes 

 like those of a Heliozoon, and remain very sluggish. The 



FIG. 85. Female reproductive organs of Crayfish. 

 (After SUCKOW.) 



ov, Ovaries ; ov' , fused posterior part ; od, oviduct : vu, female 

 aperture on the second walking leg. 



seminal fluid is milky in appearance, and becomes thicker 

 in its passage through the genital ducts. It is possible that 

 the genital ducts represent modified nephridia, and that the 

 cavities of the gonads are coelomic. 



The ovaries are like the testes, but more compact. The 

 eggs are liberated into the cavity of the organ, and pass out 

 by short thick oviducts opening on the second pair of 

 walking legs. As they are laid they seem to be coated with 

 the secretion of the cement glands of the abdomen, and the 



