490 H. F. MOORE. [Vol. X. 



muscle layer about in line with the ventral couple of setae, 

 and then follow the course of the circular muscles, giving 

 off branches to the hypodermis and longitudinal muscle 

 bundles. 



Ncphridia. — The nephridia are paired in each somite, be- 

 ginning in IV, where they are smaller than in the somites suc- 

 ceeding. The external opening is near the ventral couple of 

 setae. These organs appear to present no differences from 

 those of Lumbricus. 



The principal facts treated in the foregoing paper are as 

 follows : 



1. Behind each seta of the ventral couples in somites XIII 

 and XVI are sac-like invaginations of the setigerous follicles 

 receiving the secretion from long-necked granular cells, the 

 swollen inner ends of which lie within the body cavity. 



2. Around the atrial cavity are thick walls of club-shaped 

 unicellular glands of two kinds. The clear cells of the upper 

 portion secrete chitin for the manufacture of the spermato- 

 phore, the latter being fabricated in the atrial cavity. The 

 granular cells which form the basal portion of the anterior lobe 

 and all of the posterior lobe of the prostate, open around the 

 male genital pore, and resemble the secreting cells of the post- 

 setal glands. 



3. The coelomic end of the oviduct forms a ciliated disc 

 which is directly invaginated into somite XIV to form the 

 ovisac. The oviduct is covered by a tunic containing muscle 

 fibres. 



4. The sperm ducts on each side join far back in somite 

 XIII. 



5. A structure similar to the calciferous glands of Lumbri- 

 cus is described and compared with Claparede's description of 

 Lumbricus terrestris. 



Following is a definition of the genus : 



Genus Bimastos, H. F. M. (9). 



1. Prostomium continued on peristomium by grooves. 



2. Clitellum on XXIII to XXVIII, complete. 



3. Setae in four couples. 



