AND OTHER FAMIIilES. 177 



the cavity of the beaks; cavity of the beaks shallow and subangular; 

 nacre white and iridescent. 



Eemarks. — This beautiful little species I procured from the cabinet 

 of the Duke de Rivoli in Paris. It appears to me to be inedited, and 

 may perhaps have been considered a transverse variety of the corru- 

 gatus (Lam.). It ought not to be confounded with that species, 

 being much more transverse, and the folds of the beaks differing. 

 Lamarck, in his description of the corrugafus, says, " rugis angulato- 

 flexuosis." The folds of the dimrimtus are well marked, without an- 

 gles, and diverge from the point of the beaks. 



Unio Corrianus. Plate IX. fig. 25. 



Testa angusto-ellipticd, iransversissimd, valde insequilaterd, postice subangu- 

 lata; valvulis tenuissimis ; natibus vix prominulis ; dentibus cardinalibiis tenuibus 

 et laminatis ; lateralibus longis, tenuibus, subrectisque ; margaritd albd et irides- 

 cente. 



Shell narrow-elliptical, very transverse, very inequilateral, subangular behind ; valves 

 very thin ; beaks scarcely prominent ; cardinal teeth thin and bladed ; lateral teeth long, 

 thin and nearly straight ; nacre pearly white and iridescent. 



Hab. India. Mrs Corrie. 



My Cabinet. 

 Cabinet of the Academy of Natural Sciences of Philadelphia. 

 Diam. -6, Length 1, Breadth 2-1 inches. 



Shell narrow elliptical, very transverse, very inequilateral, subangu- 

 lar behind ; dorsal line nearly straight; substance of the shell very thin ; 

 beaks very slightly elevated and minutely waved at the tip ; ligament 

 long and slender ; epidermis smooth, dark brown ; rays none ; cardinal 

 teeth thin, bladed, single in the lefi valve and double in the right; 

 lateral teeth long, thin, bladed and nearly straight; anterior cicatrices 

 distinct ; posterior cicatrices confluent ; dorsal cicatrices situated nearly 

 in the centre of the cavity of the beaks ; cavity of the beaks exceed- 

 ingly shallow ; nacre pearly white and iridescent. 

 47 



