306 BULLETIN OF THE BUREAU OF FISHERIES. 



THE SEMINAL VESICLE. 



The seminal vesicle is deposited on the sternum of the female between the last 

 three pairs of legs and is composed of a dark gray or black material which has the con- 

 sistency of whalebone. Males taken in July and August contain a dark gray, waxy 

 material in a coiled tube under the carapace. This seems to be the material of which 

 the seminal vesicle is composed. 



The interior of the seminal vesicle is porous and has much the appearance of a piece 

 of coarse, dry bread, which suggests that the material contained in the testes and vas 

 deferens of the male during the mating season is composed of two different substances. 

 One substance, which hardens soon after being deposited upon the sternum of the 

 female, forms the bulk and body of the vesicle, while the other substance remains liquid. 

 This liquid does not harden, since it can be expressed when the surface of the vesicle is 

 scraped away. These two substances, however, form a homogeneous waxy fluid before 

 the vesicle is deposited, and they are probably separated from each other by the process 

 of hardening of the waxy material around the liquid, the pores being formed in a way 

 analogous to the air bubbles in thick glue, or molten glass. A large part of the old 

 vesicle is picked off by the females with the fifth dactyls soon after the eggs hatch. In 

 three instances it was observed that molting took place from three to five days after the 

 eggs had hatched. The end of the spawning season and the beginning of the molting 

 season of the female are indicated by the condition of the seminal vesicle. 



SPAWNING. 



AGE OF FEMALE AT SEXUAL MATURITY. 



The age at which the female reaches sexual maturity is not definitely known, but, 

 judging by the development of the secondary sexual characteristics, the female reaches 

 sexual maturity at a smaller size than the male. The smallest females observed carry- 

 ing spawn measured 3 inches on the carapace, or about 9 inches in total length, exclusive 

 of the antennae. The size of spawn-bearing females varies considerably, the variation 

 probably indicating differences in age. 



THE SPAWNING ACT. 



One spiny lobster was observed closely while spawning was taking place. The posi- 

 tion of the female was that which is normally assumed while at rest and not upon its 

 back. The abdomen was flexed, and the uropods formed a pocket with the exopodites 

 of the pleopods. The fifth legs moved rapidly from the seminal vesicle to the pleopods 

 during short intervals and then remained at rest. The vesicle was scraped frequently 

 with the fifth and sometimes with the fourth pair of dactyls. The exopodites of the 

 pleopods beat slowly and rhythmically at times, the movement being from side to side. 

 The pleopods remained inactive and extended while the vesicle was being scraped, and 

 they moved rapidly while the fifth pair of legs moved backward to them. 



DEPOSITION OF EGGS. 



The eggs were not seen as they left the oviduct and passed to the pleopods, nor was 

 the method by which they are attached to the setae observed. The eggs are fastened to 

 the setae in bunches of different sizes, which indicates that they were laid either in bunches 



