No. 2.] STRUCTURE OF BIMASTOS PALUSTRIS. 4S5 



body lying in the swollen end of the cell and containing a more 

 deeply stained nucleolus. The mouths of these cells open 

 around and just within the male genital pore. In this region 

 the ordinary hypodermal cells appear to be absent, in conse- 

 quence of which the cuticle appears to be lacking also. The 

 entire surface appears to be occupied by the apertures of the 

 unicellular glands, thus giving the lustreless appearance noticed 

 in the description of the external characters. 



These granular cells are in appearance and arrangement 

 quite like those of the post-setal glands, and it is probable that 

 they are morphologically equivalent. 



In a portion of the lower third of the prostate forming a 

 zone between the orifices of the granular cells and of the chiti- 

 nogefious cells, respectively, there is a continuous lining of 

 columnar cells with well defined boundaries and containing 

 oval nuclei and nucleoli (Fig. 17). Just without this lining 

 lies the mass of granular cells forming the thickness of the organ, 

 but their ducts, instead of passing directly to the atrial cavity, 

 pass ventralwards parallel to the lining epithelial layer, to open, 

 as above stated, in the neighborhood of the external pore 

 (Fig. 14). 



The cells which I have designated chitinogenous glands are 

 without much doubt derived from the general columnar cells 

 lining the atrium. They are certainly not hypertrophied cells 

 of the coelomic layer, for, as has been pointed out, this exists 

 as a distinct though delicate membrane covering the glandular 

 mass upon its coelomic surface. 



The lobe of the "prostate" lying in somite XVI appears to 

 contain the granular gland cells only. 



The glandular mass surrounding the terminus of the sperm 

 canal differs, then, in several respects from the similar organ 

 which has been described in other earthworms. In the first 

 place, two distinct forms of gland cells are found, lying in dif- 

 ferent regions and secreting diverse products. 



I believe that the chitin-producing upper portion of the mass 

 corresponds with the prostates of Moniligaster, Acanthodrilus 

 (2 and 5), etc., and that the granular cells opening in the neigh- 

 borhood of the genital pore are to be considered in connection 



