76 DESCRIPTION OF NEW 



Unio Menkianus. Plate XIX. fig. 59. 



Testa ellipticd, subcompressd, incequilaterali, valvulis subtenuibus ; natibus subprominenti- 

 bus undulatisque ; epidermide fulvd et muUiradiatd ; denlibus cardinalibus parvis eredisque ; 

 lateralibus longis subrectisque ; margaritd alba et iridescente. 



Shell elliptical, rather compressed, inequilateral ; valves rather thin ; beaks some- 

 what prominent and undulated ; epidermis yellow and much rayed ; cardinal teeth 

 small and erect ; lateral teeth long and nearly straight ; nacre pearly white and iri- 

 descent. 



Hab. Harpeth River, Ten. Professor Troost. 



My Cabinet. 



Cabinet of Professor Troost. 



Diam. -9, Length 1'5, Breadth 2-5 inches. 



Shell elliptical, rather compressed, inequilateral, radiated over the 

 whole disk; substance of the shell thin behind, thicker before; beaks 

 somewhat prominent and undulated at tip; ligament rather long and 

 thin; epidermis yellow, rather smooth, with numerous rather large, 

 green rays, radiating to all parts of the margin ; cardinal teeth small, 

 conical, deeply cleft in the left valve ; lateral teeth long and nearly 

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

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

 the shell rather shallow; cavity of the beaks rather small and subangu- 

 lar; nacre pearly white and iridescent. 



Remarks.— This is another new species of the many I owe to the 

 kindness of Professor Troost. It has some resemblance to U. interrup- 

 tus (nobis), and may be said to connect that shell with U. crassus (Say). 

 The two specimens which I have before me are covered with beautiful 

 green rays over the whole disk, they being thicker and darker on the 

 posterior half. The undulations of the beaks are small and numerous. 

 I name it after the able German conchologist, Dr Menke. 



