292 



Records of the Indian Museum. [Voi,. XVI, 



Parrcyssia, Conrad. 



Ortmann ' has described the animals of this genus and of 

 Lamellidens. I have unfortunately not been able to see the original 

 papers but have consulted his later publication,* in which he has 

 given a fairly complete resume of his first paper. 



The animal (fig. 3) may be described as follows :— The gills are 

 three to five times as long as broad. Anteriorly the outer pair of 

 gills is a little shorter than the inner, so that the margin of the latter 

 projects beyond that of the former. The inner lamellae of the 

 inner pair of gills are connected along more than three fourths of 

 their length to the abdominal sac : the posterior one fourth part 

 unites with the lamella of the opposite side to form the diaphragm ; 

 other connections of the gills are the same as in Balwantia des- 

 cribed already. All the four gills are marsupial. The margin of 



p: 



I.G. 



Text-fig. 3. — Animal of Pavreyssia fdvidens, reference lettering^ same as in 

 Hg. I. 



the gills, even when full of glochidia, is quite sharp. The water- 

 tubes are simple and the placentae are slightly compressed, 

 elongate structures. The palpi are well developed, sub triangular 

 with a broad base, along which they are attached to the abdominal 

 mass and have the free outer angle rounded. The mantle has a 

 slightly thickened entire margin. The foot is \-ery large, occupying 

 about half of the shell cavity. The branchial aperture is large 

 with three rows of small pointed papillae of a Hght brown colour. 

 The anal is less than half the size of the branchial and is marked 

 off from it by a feebly developed ridge of the mantle. The supra- 

 anal is of the same size or a little larger than the mantle connec- 

 tion between it and the anal. 



The glochidia ^ are semi-circular or semi-elliptic. 



1 Nautilus, XXIII, pp. 13Q-142 (1910) and XXIV, pp. 103-108 (1911). 



2 Ann. Cai-negie Mus., \\\, pp. 222-365 (1011-12). 



- Vcc. Ind. Mus., XV, pp. 145-146 (1918), may be consulted for details. 



