THE ESOGONE^:. 



235 



of the same genus — G. pfotandrica. In G. pusilloides there is no protandry, 

 so far as I have been able to observe — active sperms and maturing ova 

 occurring together. 



In a sexually mature specimen, before oviposition takes place, one large 

 ovum is found in each of the 11th or 12th to the 16th or 17th segments 

 (text-fig. 2). Each of these is lodged in a thin-walled sac formed by the 

 union of the two nephridia of the segment and opening on the exterior by 

 the two nephridiopores, situated just in front of the parapodia on the ventral 

 side. 



Text-tis. 2. 



^]d,£ 



Development of ovum in Grtibea pusilloides. 



(he, dorsal cirrus; L, intestine; n.c, ventral nerve-cord; np., nepkridiopore ; 



ov., ovum : m.c, ventral cirrus. 



The testes are developed as small irregular bodies in close connection with 

 the nephridia in the 9th and 10th or 10th and 11th segments. There is no 

 union between the nephridia of opposite sides. The sperms in the 9th seg- 

 ment collect in the posterior part of the segment and doubtless are taken up 

 by the ciliated funnels, and passed to the exterior through the nephridia of 

 the 10th segment. Sperms still remain active in specimens with three 

 externally attached ova. In specimens with the full number (five) of 

 external ova attached to the 10th to 15th segments sperms were still to be 

 found in the male segments in front. 



De St. Joseph states (31. p. 79) that in G. pusilla the female has two eggs 

 attached to each segment from the 10th to the 26th. 



In Splimrosyllu Jiystrix in the male the early development of the nephridia 

 and testes takes place very much as in Exogone fustifera. Later the inner 

 portions of the testes unite in the middle line. In mature males with the 

 cajloii! full of sperms, the two nephridia of each segment, which remain 

 quite separate from one another, have assumed the form of coiled thick- 

 walled tubes with degenerate epithelium. In the female the two ova 

 developed in each segment (PI. 18. fig. 16) are in early stages of growth 

 each enclosed in a sac with a wall composed of a single layer of cells and 

 apparently corresponding to the nepbridial sac of other Exogonew. But in 

 specimens with full-grown ova this investment has completely lost its cellular 

 character and has quite the appearance of a cuticle. 



