SEA-FISHERIES LABORATORY. 217 



measure *06 mm., and appear as oval bodies with a thin 

 vitelline membrane. The cell contents are finely 

 granular. The nucleus is a large oval body, with a sharp 

 outline. A single rounded nucleolus is also present. 

 After passing into the genital segment the cell contents 

 increase in amount, causing a great enlargement of the 

 egg, which finally passes out at the opening between the 

 vulva and the lateral margin of the segment, already 

 described. As the eggs pass out they are probably 

 fertilised by the spermatozoa from the " receptaculum 

 seminis." They are then enclosed in a thin chitinous 

 tube, secreted by the cement gland, which gradually 

 extends as more eggs are expelled. The ovisacs are often 

 longer than the animal. The eggs in this tube are 

 biscuit-shaped, measuring '36 mm. in diameter and 

 '11 mm. in thickness. They are arranged in a single 

 column. When the animal is irritated the tubes are 

 frequently detached. When the embryos hatch, the 

 empty, ruptured tube is left, and remains attached to the 

 animal for a time. After examining many specimens, 

 the conclusion has been come to that additional eggs are 

 not developed in the tubules of the ovary after the first 

 lot have been expelled. Adult females in which the 

 ovary is only an empty sac are not uncommon. 



Life History. 



Lcpeofhtheirus has no regular breeding season. Mature 

 females with ovisacs may be found at all times. The 

 state of development reached by the embryos carried by 

 various females collected at the same time is frequently 

 widely different. In some the germinal disc has just 

 begun to segment, in others the larvse are ready to hatch. 



The changes that take place in the developing embryo 

 have not been worked out by the author. The period of 



