AND OTHER FAMILIES. 65 



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

 nacre white and iridescent. 



Remarks. — 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- 

 gatiis (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 corrugatm, says, " rugis angulato- 

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

 gles, and diverge from the point of the beaks. 



Unio Corrianus. Plate IX. figr. 25 



»• 



Testa angusto-elUpticu, transversissima, valde inseqidlaterii, postice subangu- 

 latd; valvidis tenuissimis ; natibus vix pro7ninulis ; dentibus cardinalibus tenuibus 

 et laminatis ; lateralibus longis, ienuibiis, siibi'ectisque ; 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. 



Hah. 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 left 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. 



VOL. V. R 



