234 EDWIN S. GOODRICH. 



would be more correct to call itj^ removed from a female 

 Sternaspis^ the oviducts having been cut through near their 

 attachment to the body-wall. These ducts pass forward and 

 open to the exterior at the end of the processes seen in fig. 16, 

 in front of segment 8. 



When viewed from the dorsal surface the two ducts appear 

 to be simple tubes, uniting and passing into, or expanding to 

 form, the lobulated genital sac. 



When viewed from the ventral surface, however, we see that 

 on either side a small blood-vessel, lat. v., fig. 1, comes off 

 from the large ventral vessel, v. v., passes along the inner 

 surface of the wall of the sac for a short distance, and then 

 emerges on the outer surface of the duct down which it runs 

 to the body-wall. Now this blood-vessel passes out from the 

 genital sac by an open canal formed by the folding of a ciliated 

 membrane, op. The edge of this membrane forms a sort of 

 ciliated funnel, cil. mb., opening into the coelom, and is pro- 

 duced as a ciliated ridge down the outer and ventral side of 

 the duct for about two thirds of its length. 



The exact conformation of the ccelomic opening of the 

 genital sac will be better understood on looking at the series 

 of sections represented in figs. 2 — 8. Fig. 2 is taken through 

 the narrow region connecting the sac with the ducts ; fig. 3 

 is through the same region, but nearer their point of origin. 

 Although the blood-vessels lie in the wall of the sac, the ciliated 

 epithelium never covers them. In fig. 4, a section immediately 

 after the bifurcation, the beginning of a ridge is visible pro- 

 jecting into the lumen of each duct. In fig. 5 this ridge is 

 seen to project far inwards in the upper section, whilst in the 

 lower section it has cut the lumen completely into two. The 

 blood-vessel, lat. v., has passed into the ventral and smaller 

 lumen. The sections represented in fig. 6 show the blood- 

 vessel lying near the edge of the ciliated membrane, so as to 

 close the aperture of the funnel, which is seen to be widely 



1 The ova and spermatozoa are developed on the walls of the branches of 

 the ventral vessel, which enter the sacs near the point of bifurcation of the 

 genital ducts. 



