No. 2.] STRUCTURE OF BIMASTOS PALUSTRIS. 477 



setigerous glands, we find some remarkable structures, which 

 resemble the glandular masses found upon the ventral faces of 

 certain somites in species of Lumbricus, Allolobophora, and 

 Allurus. 



Behind each seta of the ventral pairs, on somites XIII and 

 XVI, we find sac-like invaginations of the hypodermis, the out- 

 lets of which lie just within the mouths of the setigerous 

 glands. The relations of these invaginated pouches to the 

 setae remind one of the sebaceous glands of a hair follicle. 

 The cuticle extends a short distance into the mouths of these 

 pouches, thins out, and disappears. The ordinary hypodermal 

 cells wall the outer two-thirds of the pouch, which about equals 

 in depth the thickness of the circular muscle-layer. Into the 

 deeper third open the numerous mouths of unicellular glands, 

 flask-shaped cells with very long and slender necks. 



These gland-cells lie on the inner face of the body-wall, the 

 cell aggregate projecting into the body cavity, and being 

 covered internally by the coelomic lining only. They are 

 filled with a granular material, and in the head may be distin- 

 guished a nucleus and nucleolus, somewhat clearer than the 

 surrounding protoplasm. 



The long necks of these cells, which are the more granular 

 portions, pass, parellel to one another, in a fasciculus through 

 the longitudinal muscle-layer, and empty, as aforesaid, into the 

 deeper portions of the invaginated sac. The latter, in my 

 specimens, was filled with an apparently mucoid material, 

 which may be of utility in causing adhesion of the worms 

 during copulation. 



These glands are advantageously situated to pour out their 

 secretion along the setae. They do not occur in the somites 

 bearing the genital openings, nor were they met with else- 

 where. They must be regarded as a simple form of multicel- 

 lular hypodermal gland. The long-necked flask-cells are mani- 

 festly hypodermal in origin. That they are not of coelomic 

 origin is probable from the continuity of the coelomic mem- 

 brane over their inner surface. They appear to be similar to 

 certain cells forming a portion of the prostate. 



The hypodermis is otherwise modified in the region of the 



