ACANTHOCE PIT ALA. 



361 



FlO. 292. Embryo of Echin- 

 orhynchug g>gus enclosed in 

 the egg membranes (after 

 Leuckurt) . 



and 291, Li}. The sexes are separate. The male (fig. 290) has two 

 testes (T), and the same number of efferent ducts (Vd). The latter 

 unite behind to form a ductus ejaculatorius (De), which is often fur- 

 nished with six or eight glandular sacs (Pr), and a conical penis (P), 

 at the bottom of a bell-shaped protrusible bursa (7?), situated at the 

 posterior pole of the body (fig. 290). The generative organs of the 

 larger females (fig. 291) consist of the ovary 

 developed in the ligament ; of a complicated 

 uterine bell, beginning with a free opening 

 into the body cavity ; of the oviduct and the 

 short vagina, which is divided into several 

 portions and opens at the posterior end of 

 the body (fig. 291). It is only in the young 

 stage that the ovary is a simple body en- 

 closed by the membrane of the above-men- 

 tioned ligament. As the animal increases in 

 size, the ovary grows, and becomes divided 

 into numerous spherical masses of eggs, the 

 pressure of which bursts the membrane of the ligament ; the masses 

 of ova as well as the ripe elliptical eggs, which gradually become free 

 from them, fall into the body cavity. The egg membranes are not 



formed till 



a. 7, c (^ d g^ a fter seg- 



mentation, 

 and ought 

 perhapsto be 

 interpreted 

 as embryo- 

 nic mem- 

 branes. The 

 eggs, which 

 already con- 

 tain em- 

 bryos, pass 

 out of the 

 body cavity 

 into the 

 uterine bell, 

 which is 

 continually 



dilating and contracting, thence into the oviduct, and through the 

 genital opening to the exterior. 



FIG. 293. Larvae of EcJiinorhyncJivi prof, 13 from Gamniarus (aftei 

 Leuckart). a, Free embryo ; ETe, embryonic nucleus, b. Older stapo, 

 with more differentiated embryonic nucleus, c, Young female worm ; 

 Ov, ovary, d, A young male worm ; T, testes ; Le, lemnisci. 



