206 W. B. BENHAM. 



tion with the spermathecse, have been distinguished by Horst 

 as " copulatory setse/^ Tiiese two terms are, to all intents 

 and purposes, identical : so that I shall distinguish penial setse 

 in the neighbourhood of the prostates, or spermiducal pores 

 as " male copulatory setae,^^ or '^ posterior penial setae,'^ and 

 those in neighbourhood of spermathecse, as "female copu- 

 latory,''' or " anterior penial setse." 



Certain terms in connection with the internal reproduc- 

 tive apparatus may require definition. The testes are 

 usually present to the number of two pairs, and these are nearly 

 always placed in Somites x and xi. The difficulty in counting 

 the somites, or the delicacy and fragility of the septa, some- 

 times render it difficult to be certain of the true position of 

 the testes, especially as in some worms the septa do not 

 correspond exactly in position to the true limits of the 

 somites ; hence it may be that some, at any rate, of the excep- 

 tions are apparent rather than real. The ovaries likewise 

 are nearly universally placed in the Somite xiii ; the oviducts 

 open externally on the Somite xiv. 



The terms vesiculae seminales, and seminal reservoirs, are con- 

 veniently replaced by "sperm-sacs" (i. e. the '^testes'' of the 

 older authors). Similarly the rather clumsy term " recepta- 

 culum ovorum," which has been observed in several worms, 

 may be replaced by " ovisac ; " a word at the same time 

 simpler than the original term, and also in agreement with 

 '' sperm-sac,'^ both in nomenclature and in function. 



I shall use the word " sperm-duct" for the more old- 

 fashioned "vas deferens;" however, I shall retain '^ciliated 

 rosette" as a more convenient and shorter term than "funnel 

 of the sperm-duct." 



In many genera there is, attached to the sperm-duct near 

 its external pore, a glandular diverticulum, which may be lobed 

 as in Perichseta, or tubular and coiled as in Pontodrilus, 

 and others. Most writers have referred to these structures as 

 " prostates ; " but Beddard has recently, in two papers (' Zool. 

 Anz./ No. 268, 1887, and ' Quart. Journ. Micr. Sci.,' xxix, 

 p. 117), sought to establish an homology between these pro- 



