174 ON THE NAIADES, 



interrupted one like the pustulosus. There is a great peculiarity in 

 the flesh or pink colour of the nacre, which is disposed to be clouded, 

 and to be of a stronger hue about the teeth, while the cavity of the 

 beak is nearly white. 



I dedicate this species to my friend, William Cooper, Esq., as a slight 

 acknowledgement of the many favours received in the way of commu- 

 nications, and the loan of specimens. 



Unio emarginatus. Plate IX. fig. 22. 



Testd sub-ellipticd, ad basim emarginatd et compressu, transversissimd, valde 

 inaequilateru, postice sub-triangidatu ; valvitUs fiubcrassis ; naiibus prominulis, 

 apicibus undiilatis ; epiderniide viridi-luteu ; dentibus cardinalibiis parvis, obliquis, 

 et in valvula utrdque dvplicibus ; lateralibus longis subcurvisque ; margaritd 

 alba et iridescente. 



Shell sub-elliptical, emarginate and compressed at base, very transverse, very inequi- 

 lateral, sub-biangular behind ; valves somewhat thick; beaks rather elevated and undu- 

 lated at tip; epidermis greenish yellow; cardinal teeth small, oblique and double in 

 both valves ; lateral teeth long and slightly curved ; nacre pearly white and iridescent. 



Hab 



My Cabinet. 

 Diam. 1, Length 1-3, Breadth 2-8 inches. 



Shell subelliptical, emarginate and compressed at base, very trans- 

 verse, very inequilateral, sub-biangular behind, elevated along the um- 

 bonial slope, flattened on the umbones ; substance of the shell somewhat 

 thick ; beaks rather elevated, retuse and undulate at the tip ; ligament 

 long and thin ; epidermis finely wrinkled, greenish yellow, along the 

 posterior slope green ; cardinal teeth small, oblique and double in both 

 valves ; lateral teeth long and slightly curved ; anterior cicatrices dis- 

 tinct ; posterior cicatrices confluent ; dorsal cicatrices situated on the 

 under part of the cardinal tooth ; cavity of the beaks subangular and 

 wide ; nacre pearly white and iridescent. 



Remarks. — I procured two opposed valves of different individuals of 

 this species, which nearly match, of Mr Stutchbury, a well known and 



