■6U COMPARATIVE ANATOMY. 



Generative Organs. 



§ 246. 



Ill some of tlie Bracliiopoda the arrangement of the generative 

 organs is hermaphrodite, so that the separation of the sexes seems 

 to be an exception (Thecidium). The organs merely consist of 

 germinal glands, in which the sperm and ova are formed. In the 

 hermaphrodite form there are four, and in Thecidium two, glandular 

 masses. In the Ecardines they lie in the coelom, partly surround- 

 ing the enteron and the muscles; in the Testicardines they form 

 rounded masses in the cavity of the two lamellae of the mantle (con- 

 tinuations of the coelom) (Fig, 165, g); in either case they call to 

 mind the character of the generative organs of the Gephyrea, and of 

 the Annelides. In the dioecious forms they are ovaries in one, and 

 testes in the other. It is not known what relation there is between 

 the ovarian and seminal regions in the monoecious forms. The 

 generative products escape into the coelom. 



The excretory organs act as the efferent ducts of the generative 

 glands, so that here too a primitively unconnected apparatus func- 

 tions as an oviduct, or as a seminal duct, according to the sex. 



