464 Illinois State Laboratori/ of Natardl History. 



the ventral side of its cavity. Each of the sperm- ducts con- 

 nected with the posterior funnels extends at first directly 

 downward, and then, bending posteriorly, takes a quite direct 

 course to the muscular duct, which it follows to the sperm- 

 reservoir. Passing then through the muscular coat of that 

 organ it extends posteriorly, having the same relation to the 

 muscle layer and lining epithelium as has the duct from the 

 anterior funnel, except that it lies on the dorsal instead of 

 the ventral side of the cavity and opens into the chamber at 

 a point nearly opposite the opening of the anterior duct. 



Each sperm-reservoir lies in the sperm-sac of its own side, 

 and extends from the posterior part of X or the anterior part 

 of XI for a distance of six to eight somites. This organ has 

 powerful muscular walls, which are not constricted by the 

 septa, and which consist of a thin inner epithelial layer, a 

 thin layer of circular muscle fibers, and an outer and much 

 thicker layer of muscle fibers which are nearly longitudinal 

 but have a somewhat spiral course. Numerous large cells, 

 apparently glandular in nature, lie outside the reservoir, and 

 are connected with its wall by elongated narrowed extensions 

 which presumably function as ducts, but have not been fol- 

 lowed beyond the superficial portion of the muscular wall. 

 The cells are altogether similar to those figured and described 

 by Eisen ('95, p. 88) as being numerous about the anterior 

 end of the "storage chamhev'' o( Eclijiidrilus frigidus. In 

 Premnodrilns jxiliistris, however, they are more abundant 

 near the posterior end of the chamber, and much less frequent 

 at the anterior end. Besides these large prostate glands, 

 following Eisen's nomenclature, there is a more or less inter- 

 rupted layer of smaller cells much like those called by Eisen 

 small prostate glands. The inner epithelium is everywhere 

 thin and the cell walls are indistinguishable. 



Throughout the greater part of its length the sperm- 

 reservoir, exclusive of the layer of prostate cells, has a 

 diameter of about .25 mm., that of its lumen being about 

 .08 to .09 mm. The diameter of the reservoir diminishes 

 more gradually toward the anterior end than toward the 

 posterior, and the chamber tapers ofi' into a muscular duct 



