14 - DESCRIPTION OF NEW 



ing more capillary. In the elevation and retuseness of the beaks it 

 resembles the U. pyramidatus (nobis), but differs in the depression be- 

 fore the umbonial slope in that shell, and in being white in the nacre, 

 while that species is red. The undulations of the beaks can only be 

 observed when the shell is perfect there, and I have observed it so but 

 in very young individuals. 



Unio Hydianus. Plate VI. fig. 14. 



Testa elliptica, transversa, radiatd, valde incequilaterali, subinflata ; valvidis subcrassis ; 

 dentibus cardinalibus elevatis ; lateralibus longis, a cardinalibus separatis ; margaritu alba et 

 iridescente. 



Shell elliptical, transverse, rayed, very inequilateral, somewhat inflated ; valves rather 

 thick; cardinal teeth elevated; lateral teeth long and separated from the cardinal teeth ; 

 nacre pearly white and iridescent. 



Hab. Teche River, Louisiana. W. M. Stewart. 

 Vicinity of New Orleans. Mr Earabino. 



My Cabinet. 

 Cabinet of Mr Stewart. 

 Cabinet of Mr Hyde. 

 Diam. 1*1, Length 1-4, Breadth 2*5 inches. 



Shell elliptical, transverse, usually beautifully rayed, very inequila- 

 teral, somewhat inflated ; substance of the shell rather thick ; beaks 

 placed near the anterior margin ; ligament rather long; epidermis yel- 

 low; rays dark green and extending over the disk; cardinal teeth dou- 

 ble in both valves, erect, conical; lateral teeth rather long, slightly 

 curved; anterior cicatrices distinct; posterior cicatrices confluent ; dor- 

 sal cicatrices placed in the centre of the cavity of the beaks ; palleal 

 impression indistinct ; cavity of the shell deep ; cavity of the beaks sub- 

 angular ; nacre beautifully pearly white and iridescent. 



Remarks. The beautiful specimen figured here I owe to the kind- 

 ness of Mr W. M. Stewart, who brought it from Louisiana about three 

 years ago. It belongs to the group which contains Viiio radiata 



