248 DISCOVERY REPORTS 



body, then runs between the stalks of the two "prostates" (v. infra), and finally pene- 

 trates the junction of the two stalks and the mass of cells which mingles with them where 

 they abut on the surface. 



The "prostate" glands, in segment xii, are very large, and lie, one anterior and the 

 other posterior in position, against the lateral body-wall; the hinder end of the anterior 

 touches the front end of the posterior gland. Each is a solid mass, in length 240-3 20 /j. 

 by about 280 /^ in breadth, and is rather deeply lobed; the cells are prolonged into much 

 elongated and fine thread-like stalks, along which the secretion probably passes, and 

 which are aggregated to form a stalk for each gland ; these stalks enter the body-wall, 

 converge, and meet at the surface. 



There is no definite penial body, that is, no definitely limited, spherical, encapsuled 

 mass, composed mainly of elongated cells abutting on the terminal part of the vas 

 deferens and the surface invagination into which the vas discharges. The stalks of the 

 prostates, however, are enclosed in a loose mass of muscular fibres which run in many 

 directions — a spongy mass, not of very definite outline, and not encapsuled but con- 

 tinuous with the tissues of the body-wall. This mass fills out the interior of the porophore, 

 a projection of some size, at the tip of which is a special rounded aggregate, 100 /x high, 

 of moderately deeply staining cells derived from the surface epithelium ; the stalks of the 

 prostates, and also the vas deferens, enter and come to the surface through this aggre- 

 gate, the elements of which the stalks are composed (the prolongations of the gland 

 cells) mingling indistinguishably with the cells. 



There is a much greater amount of muscular tissue in this "bulb" than in the 

 corresponding structure of M. grisea; the mass has a vertical thickness of about 250/x, 

 and envelopes the whole of the stalks of the prostates, comes into extensive contact with 

 the base of the glands, and even surrounds their lower parts. 



Many muscular strands pass inwards from the body-wall in the region of the male pores. 



The spermathecal apparatus on each side (ampulla plus duct) forms a tube, the 

 diameter of which does not vary very much from one part to another, the ampulla, 

 however, being rather narrower than the duct (diameter of ampulla 70/x, of duct 85/x ; or 

 ampulla 61 ju, duct 74/^), and about equal to it in length (about 160 /x). The ampulla 

 communicates by a patent passage with the oesophagus ; in one specimen a plug, com- 

 posed of the tails of spermatozoa, occupies the tubular passage through the oesophageal 

 wall. Though there is no very sharp external limitation between ampulla and duct, the 

 character of the epithelium of these two parts is quite different ; the high clear cells of 

 the duct give place abruptly to the low, more deeply staining cells of the ampulla, so 

 occasioning a sudden change in the width of the cavity of the organ. The lumen of the 

 duct contains the heads of numerous spermatozoa. 



Associated with the spermatheca of each side are two masses of gland cells, one above 

 and one below the ectal part of the duct, each mass about as thick as the duct. The stalks 

 of these gland masses enter the muscular layer of the body-wall, and probably reach the 

 surface close to the spermathecal pore ; they do not discharge into the spermathecal duct, 

 which is everywhere enclosed by a muscular investment. 



