1903 ] NATURAL SCIENCES OF PHILADELPHIA. 371 



one nucleus, and each is a single large cell containing a much con- 

 voluted, somewhat pulsatile lumen. The dorsal termination of this 

 swollen portion lies at the boundary of corona and trunk, and at that 

 point joins with the common nephridial ductule. From this ductule 

 a secondary ductule passes anteriorly for a short distance, then divides 

 into three tertiary ductules (figs. 1, 2, 6). The most median of these 

 bears the first flame cell (Fl.C. 1), and is connected with the correspond- 

 ing ductule of the opposite side by a transverse commissure (fig. 1) 

 placed above the mouth cavity. The middle tertiary ductule termi- 

 nates in the second flame cell (Fl.C. 2). The most lateral tertiary duc- 

 tule bends ventrad, then just behind the lateral antenna divides into 

 two quartern ductules, the anterior of which is very short and termi- 

 nates in the third flame cell {Fl.C. 3) placed near the lateral antenna, 

 while the posterior passes backward and follows the course of the lateral 

 canals of the nephridia, terminating in two short ductules each ending 

 in a flame cell (Fl.C. 4, Fl.C. 5). Finally, from the common nephridial 

 ductule pass backward on the dorsal surface of the trunk a pair of 

 secondary ductules, each of which terminates in a flame cell near the 

 mastax {Fl.C. 6). Cast's account differs in that he states that what 

 I term flame cells 4 and 5 connect by short ductules directly with 

 the lateral canals. 



The nephridium of one side is thereby connected with that of the 

 other at its anterior end by a commissure of the ductules, and at its 

 posterior l^y fusion of the lateral canals. The only portion of the 

 nephridia which are cihated are the terminal flame cells ; these (fig. 6) 

 are completely closed from the body cavity, and each has an intra- 

 cellular canal in which beats a long tuft of cilia (a typical "flame") 

 attached at the wall of the cell where the lumen ends; the terminal 

 end of each flame cell is somewhat enlarged, more or less amoeboid, and 

 contains one nucleus. The lumen of the ductules and of the lateral 

 canals is also intracellular; a pair of nuclei are always present on the 

 wall of the commissure connecting the anterior secondary ductules. 



Gennarium (Eierstock, Mecznikow; Keimdotterstock, Cast; ovary 

 of Stokes) has the same relations as in lentiforviis. It lies on the ven- 

 tral side of the body {Ov., figs. 2, 3) anterior to the foot, often in an 

 irregular position due to the pressure of embryos upon it, a small 

 rounded mass of cells, with a distinct cellular lining which is continued 

 backward as the unpaired oviduct {Ovd.) and joins the cloaca between 

 the openings of the nephridia and the posterior intestine. It contains 

 yolk cells (nurse cells) to the number of 10-14, large cells without dis- 

 tinct boundaries, each with a large nucleus containing a huge nucleolus. 



