NBMERTEA ENOPLA 



659 



(Text-fig. 24, D. iilbolineatus). Moreover, these sacs have, 

 as Punnet t (14, 15) showed, a pecuKar form. In more 

 rounded species, as the first, they are V-shaped (Text-fig. 23, a) 

 with the two legs above and beneath the intestine and the 

 lateral gonoduct at the place of junction of the legs. In 

 Siboganemertes this is found too, but the sperm is not developed 

 in this large sac alone. Peripherally small sacs are found 



Text-fig. 22. 



c6.Lv. 



Lb.v. 



rkyihcJi 



b. 



Sections through gonadial region : a, of Nemertopsis peron 

 after Biirger (6, PL xv, fig. 5); b, of Uniporus hyalin 

 after Brinkmann (3, PI. 1, fig. 5). 



ea 



us 



(Text-fig. 9) which open into the central V-shaped sac (Text- 

 fig. 23, h). Burger found the same development of ovaries 

 in Drepanophorus albolineatus (Text-fig. 24), one 

 egg in each sac ; but in other species the central sac itself is 

 filled with eggs or sperm (Text-fig. 23, a). It seems to me 

 that the small sacs are comparable with the gonadial sacs of 

 Uniporus, Geonemertes, Tubulanus, Malacobdella, and that 

 the central V-shaped pouch is a new growth in the Keptantia 

 and Siboganemertes. The epithelium of the central pouch, 

 whether it is simply a new gonoduct or the invaginated ectoderm 

 with the original gonopores, acquires later the function of the 

 gonadial epithelium and the original gonads disappear. In 



X X 2 



