302 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



rial. Each spermatozoan has the general shape shown in figure 59, 



Plate 42. 



The semen receptacle, the cement glands, and the intestine are 



firmly bound together by connective tissue in 

 the position shown in figure 17, and are also 

 suspended by the same tissue from the walls 

 and sides of the thorax. 



For the discharge of the contents of both the 

 receptacle and the 

 glands the contraction 

 of the dorso - ventral 

 muscles in each thorax 

 segment may well con- 

 tribute material assist- 



FiQ. 24.— The relative size 



AND SHAPE OF COMPLETED 

 PROCESSES AS SEEN IN 

 LATERAL VIEW. 



ance. 



The size of this re- 



om 



ceptacle renders it prac- 

 tically certain that there is but a single 

 union between the sexes^ and that the female 

 derives from this a sufficient quantity of 

 sperm to fertilize all the eggs she can produce 

 during her entire life. 



Spermatophores can occasionally be found 

 in position upon the bodies of very young 

 females, but they soon disappear. Evi- 

 dently they are full of spermatozoa when 

 first attached, these spermatozoa are dis- 

 charged into the semen receptacle of the 

 female, and then the old shell of the 

 spermatophore gradually decays, loosens. 



In the male the reproductive organs consist of a pair of testes which, 

 like those in the Caligidre, resemble the ovaries in their position, form, 

 and size. They are situated close to the mid-line and just above the 

 stomach. Each testis is somewhat ovate in form, the long diameter 

 inclined at an angle of about 60° to the body axis, the small end of 

 the oval turned forward. 



From this small end is given off the vas deferens, which turns 

 downward toward the ventral body wall and then backward and 

 upward approximately parallel with the body axis to the posterior 

 margin of the fourth thorax segment, where it empties into the semen 

 receptacle (fig. 26). 



In each segment of the thorax the vasa deferentia are convoluted 

 or curved in toward each other at the anterior and posterior margins 

 and away from each other at the center of the segment. They are 



Fig. 25.— Cement gland of Er- 



GASILUS CENTRARCHIDARUM. O, 



Dorsal view; b, longitudinal 

 vertical section. 



and finally falls off. 



