488 Memoirs of the Indian Museum. [Voi,. V, 



lar (inner) and longitudinal (outer) muscular investing layers ; and the covering of 

 peritoneal cells cannot be described as either tall or flat. 



The spermiducal chamber is a median depression on the ventral surface, squarish 

 in shape as seen in a transverse section of the animal, its depth and width about 40/*. 

 It is lined by cubical epithelium. 



A single sperm-sac, an anterior evagination of septum 9/10, is situated in segment 

 ix '; and a posterior sperm-sac, also single, extends backwards through several seg- 

 ments from septum 10/11. 



The ovary and ovisac have the usual positions; but I did not see any trace of 

 oviduct or ovarian funnel. 



The spermatheca is single, in segment x. Its external opening is in the middle 

 line in. furrow 9/10 ; but the organ belongs to the left side. It lies near the ventral 

 body- wall, and takes up nearly the whole of the segment in an antero-posterior direc- 

 tion. It may be described as a somewhat twisted cylinder, whose diameter reaches 

 8om, narrowing towards the external aperture to form a short duct which bends 

 downwards. The spermatozoa, which form an amorphous mass, not spermatophores, 

 are contained in the most posterior (ental) part of the chamber. Here the epithelial 

 lining is cubical ; the middle portion of the organ, much larger than the former, but 

 not separated from it by any distinct constriction, is lined by a columnar epithelium 

 with the nuclei basal; the duct has a lining of approximately cubical cells. 



Remarks. I subjoin a comparison of certain features of this worm with the speci- 

 mens described under the above name by Ditlevsen and Moore. 



Ditlevsen gives no indication of the habitat of his worm. Moore's was a littoral 

 form; cc it appears to prefer more gravelly shores and the neighbourhood of beach 

 grass, among the roots of which it may be found. In a few cases larger numbers 

 were found living gregariously between stones at half-tide on the south shore of Nau- 

 shon." The related species M. glaber (Moore, 6) flourishes best in brackish water; 

 enormous numbers were found where the saltness of the water was just barely percep- 

 tible to the taste. Dr. Annandale informs me that the salinity where the present 

 specimens were found was certainly low, but the water was distinctly brackish. At 

 the same place on the same date in 1914 the specific gravity was 1*0145 (corrected). 



The segments in the specimens here described were not, as in Moore's worm, 

 quadriannulate . 



The differences in the setae are more important. According to Ditlevsen, while 

 the hinder dorsal bundles contain single-pointed setae, all the ventral setae are bifid. 

 Moore finds the tips (< curiously variable," and single-pointed tips seem to have been 

 very much the exception ( c ' in some the tips are deeply bifid and the points long and 

 acute ; others, especially in the posterior dorsal bundles, have the upper or distal 

 point more or less reduced, and still others have a more apical notch or are appar- 

 ently entire " ) . In the present specimens all the dorsal setae behind the middle of 

 the body, and some in front of this, are single-pointed, while single-pointed setae are 

 not uncommon in the posterior ventral bundles also ; intermediate forms are com- 

 paratively rare. 





