No. 3.] SPERMATOPHORES. 3^0 



5. The Capitellid(B. 



Among the polychaetous annelids and the CapitelHdae there 

 seems to be Httle that can be said to fall in the direct line of 

 our inquiry. In very many cases the sexual products are set 

 free in the water, and external fertilization takes place without 

 the intervention of spermatophores. In Polygordiiis, according 

 to Fraipont, the whole body undergoes a regressive metamor- 

 phosis at sexual maturity ; and the sexual products, as the result, 

 perhaps, of mechanical pressure upon the body-wall, weakened 

 by almost complete atrophy, burst through, and escape into the 

 water. The animal does not survive the evacuation of its sexual 

 cells. 



In one of the CapitelHdae {Clistomastiis lineatns), according 

 to Eisig, the whole abdominal region, in which the sexual cells 

 are lodged, undergoes a histolytic metamorphosis at sexual 

 maturity ; and the sexual elements are set free by fragmentation 

 of this region. The thoracic region alone remains intact, and 

 this is supposed to be able to regenerate a new abdomen. 



In Capitella we find spermatophores, but no evidence that 

 they are ever attached to the exterior. Dr. Eisig has made a 

 number of most interesting discoveries in regard to the mode 

 of copulation and fertilization in these worms ; and although 

 they do not touch very closely the phenomena under considera- 

 tion in the leeches, I think they are not so remote as to be out 

 of place here. 



Monog. XVI. Fauna und Flora von Neapel. 18S7. pp. 284, 674-75, 790-93. 



The organs of copulation in Capitella consist of (i) two pairs 

 of modified haemal parapodia belonging to the eighth and ninth 

 somites ; (2) a copulation gland lying between the genital para- 

 podia of the ninth somite ; and (3) a pair of genital sacs in the 

 eighth segment, which function as vesicul<z seininales, vasa effer- 

 entia, and penes. The female possesses a like pair of genital 

 sacs in the same segment, and these serve not only as organs 

 of copulation {vnkxz), but also as receptaciila seniinis and ovi- 

 ducts. Dr. Eisig thinks the glandular porophore of the female, 

 like the clitellum of the oligochasta, assists in copulation by its 

 sticky secretion. 



From the position of the copulatory organs. Dr. Eisig con- 



