AND ZOOGEOGIlAPilY OF INDIAN OUGOCH^TA. 125 



111 a third paper (6) Beddard refers to a recent paper of Rosa's 

 on Desmogaster dorice, a member of another genus of Monili- 

 gastrida^ (19) ; there is here the same annular layer of muscular 

 fibres outside the lining epitlielium, and in addition muscular 

 fibres are interspersed between the bundles of glandular cells ; 

 a delicate peritoneal investment surrounds the whole. Rosa, 

 however, states that the gland cells empty into the lumen of the 

 prostate by long ducts, and the figure also indicates tha,t these 

 ducts— apparently prolongations of the cells — pierce the layer of 

 circular muscular fibres ; nevertheless, Beddard thinks it is still 

 possible to refer all that lies outside of the lining epithelium to 

 the peritoneum (using " peritoneum " in a wide sense, Beddard 

 speaks of the muscular layer also as having been developed from 

 the peritoneum). 



Beddard also gives an account of the prostate of I), hahamensis 

 (7). The gland-cells lie in groups in the interstices of a some- 

 wiiat loosely arranged muscular mass ; the ducts of the cells — 

 simply filiform prolongations of their substance — pierce the 

 muscular layer in bundles, and evidently pour their secretion 

 into the lumen. There is no peritoneal layer outside. 



Benham examined Moniligaster indicus {=Drawida rohusta) 

 (10) ; the specimens were badly preserved. The necks of the 

 glandular cells pass through the muscular coat nearly up to the 

 epithelium, but not quite. The epithelium is traversed by 

 narrow, clear tubes resembling ducts, which difier from the 

 epithelial cells in having no inner boundary. There is a coelomic 

 epithelium outside ; hence the gland cells are not peritoneal, and 

 must belong to the layer of epithelial cells. 



Bourne, in D. grandis (11), found the gland cells arranged in 

 groups, each cell, however, sending its duct to take its place 

 among the columnar cells of the epithelial lining. There are two 

 layers of muscle — one overlying the epithelial layer a.nd within 

 the glandular layer, and another outside the glandular layer ; a 

 layer of ccelomic epithelium invests the whole. 



There is thus an exti-aordinary variety in the accounts of this 

 organ. The layer of gland cells is said to be separate from the 

 epithelial layer, and to send prolongations as ducts through the 

 epithelium to the lumen ; to have outside it a peritoneal invest- 

 ment, and to have no such layer; and to belong to the epithelial 

 layer, or to the peritoneal layer. In the present species there 

 seems to be no doubt that there is a peritoneal layer outside the 

 layer of glandular cells ; but equally definitely these latter seem 

 to be altogether cut oif from the epithelial layer and the lumen 

 of the organ. I am disposed to believe that the cells belong to 

 the peritoneum rather than to the lining epithelium ; and to 

 agree with Beddard, who would hold that the presence of a 

 flattened peritoneal layer outside the glandular cells does not 

 preclude the peritoneal origin of these latter. 



In the present species the prostates (fig. 3) are situated in 



