98 OBSERVATIONS ON NAIADES, 



blance to the corrugata, Var. a (Lam.), than to any other species I 

 have seen. It differs, however, in being more transverse, in the beaks 

 being more prominent, and in their rugosities being composed of con- 

 centric undulations. 



Symphynota Bilineata. Plate XL fig. 1 9. 



7'estd subellipticd, transversa, intzquilaterali, compressd; vahulis tenuissimis; 

 posteriori margine dorsali elevatd connatdque; natibus subprominulis, imdulas 

 concentricas et duas lineas elevatas ad mar ginem -posterior em currentes, habentibus; 

 dentibus cardinalibus laminatis et in valvuld dextrd solum duplicibus; lateralibus 

 rectis; margaritd colore salmonis subtinctd. 



Shell subelliptical, transverse, inequilateral, compressed; valves very thin, poste- 

 rior dorsal margin elevated and connate ; beaks very slightly elevated, concentri- 

 cally undulate and possessing two elevated lines which pass to the posterior margin; 

 cardinal teeth lamelliform and double in the right valve only; lateral teeth straight; 

 nacre slightly salmon coloured. 



Hab. River Hoogly, Hindostan, G. W. Blakie. 



My Cabinet. 

 Cabinet of G. W. Blakie. 

 Cabinet of Dr Burrough. 

 Cabinet of the Academy of Natural Sciences. 

 Diam. -S, Length •?, Breadth 1*3 inches. 



Shell subelliptical, transverse, inequilateral, compressed, diaphanous ; 

 substance of the shell extremely thin ; beaks very slightly elevated, 

 concentrically undulate, possessing two small elevated lines which 

 pass (posterior to the umbonial slope) to the posterior margin ; valves 

 elevated into a carina and connate in the posterior dorsal margin ; dor- 

 sal margin a right line ; ligament very small ; epidermis shining, green- 

 ish yellow, darker on the posterior slope; cardinal teeth lamelliform 

 and double iu the right valve only; lateral teeth lamelliform, long 

 and straight ; posterior and anterior cicatrices both confluent ; dorsal 

 cicatrices obsolete; cavity of the beaks shallow, very wide, and 



