igiQ-J B. Prashad : The Anatomy of Indian Mollusca. 293 



Lamellidens, Simpson. 



The animal (fig. 4) may be described as follows : — ^The gills 

 are much broader in the posterior than in the anterior half of 

 their length, and the inner pair is broader than the outer through- 

 out. The inner lamellae of the inner pair of gills are attached 

 to the abdominal mass along more than half of their length 

 anteriorly, and posteriorly they are united with one another 

 to form the diaphragm. Only the outer pair of gills are marsu- 

 pial, • the entire length of the gills being filled up with glochidia 

 and the margin of the gills remaining sharp even when the}^ are 

 quite full of glochidia. The water-tubes are simple, and the 

 placentulae are flat elliptic plates, thick and broad above, thin and 

 tapering below. The palpi are rhomboidal with the angles rounded, 

 and are attached along one of the longer sides. The margin of 

 the mantle is entire and slightly thickened beyond the pallial con- 



O.G, 



P." 



Text-fig. 4. — Animal of Lamellidens marginal is, reference lettering same 

 as in fig". I. 



nection. The foot, which is elongate, is not very large. The 

 branchial aperture is comparatively large with two to three rows 

 of well-developed pointed papillae, and is of a brownish colour. 

 The anal is very much smaller than the branchial and has a row of 

 small papillae along the margin. In continuation of the attach- 

 ment of the diaphragm to the mantle of each side is a feebly 

 developed ridge separating the branchial from the anal aperture. 

 The supra-anal is a little larger than the anal and of about the 

 same size as the mantle connection between the two apertures. 

 The glochidia are semi-elliptic in outline. 



' For further details about the marsupium and glochidia see p. 145 of my 

 second paper (Rec. Ind. Miis., XV). Unfortunately there is a typographical error 

 in the statement about the margins of the gills, which reads ' sharp and distended ' 

 instead ' of sharp and not distended.' 



