922 EEPORT or COMMISSIONER OF FISH AND FISHERIES. [44j 



The atrium and prostate gland are, to begin with, entirely surrounded 

 by the cortical layer, and the prostata evidently develops only from the 

 interior matrix. While developing they burst through the cortical layer, 

 which remains as the exterior coating of the atrium (Fig. 17 a : ps.). 



From the above investigations, imperfect as they are, I think the fol-i 

 lowing facts can be considered as established : 



1. The oviduct, atrium, and penis proper do not originate on the, 

 septal tissues ', but 



2. Develop from a large gland which originates on the body wall. 



3. The oviduct and genis are originally united. 



RECEPTACLE. 



The receptacles are found in the ninth setigerous segments, and con- 

 sist of two more or less sack-like bodies, one on each side of the ventral 

 nerve trunk, and are in Tubificini attached to the body wall just in front 

 of the ventral spine fascicles, but in Telmatodrilini between the ventral 

 and dorsal fascicles. In LumbricuUdce the receptacle opens behind the 

 ventral spines, and in Enchytrceidce between certain segments. Of the 

 receptacles we can distinguish three different forms, which, however, 

 are connected by numerous intermediate ones. The most simple form 

 of the receptacle is that of a sack, gradually increasing in size from the 

 external porus to the internal apex. Such is the form in Telmatodrilus 

 and in certain species of Camptodrilns and a few other genera. The 

 upper end of such a receptacle is sometimes bent. 



In other species we find the receptacle to consist of two unequal parts,; 

 the lower oue of which is tube-like and narrow^ — a mere duct for the^ 

 spermatozoa. The upper or inner part, on the contrary, is generaJy 

 enlarged and bent, and serves mainly as a reseptacle proper. Such 

 form is met with in Tuhifex campanulatus, Ilyodrilus Ferrierii^ Ilyodrilus 

 fragilis, and in Spirosperma, in which latter genus it reaches an unusual 

 size, extending as it does through several segments. In its highest 

 developed form the receptacle consists of three different parts, one upper 

 sack-like or receptacle proper, one middle narrow tube, and one lower 

 muscular part situated nearest the external porus. Such receptacle is 

 found in Hemitubifex insignis, Limnodrilus alpestris, and L. Silvani. In- 

 termediate forms are found in Ilyodrilus sodalis, Limnodrilus ornatus, 

 &c. 



The base of the receptacle is furnished with accessory glands only in 

 two species, viz, Ilyodrilus sodalis and Hemitubifex insignis. In the 

 former species we meet with only one single gland at the base, in the 

 latter with three for each receptacle (Fig. 5 li and Fig. 6 e). 



I have as yet found spermatophores only in few species, but am in- 

 clined to believe their occurrence to be the rule rather than the excep- 

 tion. Of the spermatophores we can distinguish three different forms, 

 viz: 



a. The sperm atophore is shuttle-like, generally tapering toward one 



