SEA-FISHERIES LABORATORY. 457 



are a pair of large openings situated on the sternum of the 

 sixth thoracic somite. The thoracic sterna are not so 

 concave as those of the male, and the abdomen is not so 

 closely applied to the thorax. The abdominal locking 

 apparatus is poorly developed. The dorsal side of the 

 carapace is well arched in the mature females, and the 

 anterolateral border of the carapace is not upturned as in 

 the males. 



The OYaries (or.) are paired, and lie in a similar 

 position to the male reproductive organs. There is, how- 

 ever, a considerable posterior prolongation of each ovary. 

 As in the male, the two antero-lateral portions are 

 connected behind the pyloric fore-gut by a strand of 

 gonadial tissue, which forms a bridge over the mid-gut. 

 Behind this transverse connection each ovary is prolonged 

 backward as a narrow strip, which extends to the extreme 

 posterior end of the thorax. At the posterior extremity 

 the two prolongations fuse together in mature specimens. 

 These backward extensions of the ovaries occupy a 

 similar position to the vasa deferentia of the male ; that 

 is to say, th.ej lie above the hind-gut and below the 

 pericardium. Beneath the anterior end of the latter each 

 posterior branch is connected on its outer side with a 

 large sac, the spermatheca* (spt.). Each spermatheca is 

 continued into a short oviduct [oval.), which opens to the 

 exterior by means of the vulva on the sternum of the 

 sixth thoracic somite. 



The condition of the ova in the ovary naturally 

 depends upon the degree of maturity attained by the 

 gonads. The immature gonads are small and pale, and 

 no evidence of the presence of eggs can be detected by the 

 naked eye. The mature gonads, however, fill almost the 



* In young crabs the spermatheca is extremely small, and can 

 only be made out with difficulty. 



