70 OBSERTATIOXS ON NAIADES, 



and in its remarkable square sides. The great peculiarity of this 

 species is in its possession of a small cicatrix (which I propose to call 

 the ventral cicatrix) anterior to the central part of the cavity of the 

 shell. In no other species have I ever met with the slightest indi- 

 cation of this cicatrix, although I have examined numerous larger and 

 more globose specimens of various species with this view. 



Unio Multiplicatus. Plate IV. fia;. 2. 



»• 



Testa trapeziali, ineequivalvi, oblique transversa, maxime undulatu ; valvulis 

 a'assissimis ; dentibus cardinalibus crassis, lateralibus longis curvisque; margaritd 

 alba et iridescente. 



Shell trapezoidal, inequivalve, obliquely transverse, much undulated ; valves very 

 thick ; cardinal teeth thick ; lateral teeth long and curved ; nacre pearly white and 

 iridescent. 



TT , C Tennessee River. Prof. Vauuxem. 



^^^- I Ohio River. T. G. Lea. 



My Cabinet. 



Cabinet of Prof. Vanuxem. 



Diara. 2'2, Length 3-S, Breadth 5-6 inches. 



Shell trapezoidal, obliquely transverse, undulated except near the 

 anterior margin, compressed towards basal and posterior margins ; 

 undulations diverge from the umbonial slope and in the superior part 

 curve towards the dorsal margin which is carinate ; substance of the 

 shell very thick ; beaks slightly prominent and rugose with undulations 

 extending over the umbones which are flattened ; ligament large, long 

 and curved ; epidermis black and much wrinkled ; cardinal teeth thick 

 and sulcate ; lateral teeth large, long and slightly curved ; anterior 

 cicatrices distinct ; posterior cicatrices confluent ; dorsal cicatrices 

 situated on the under side of the plate between the cardinal and lateral 

 teeth ; cavity of the beaks rather large and rounded ; nacre pearly 

 white, iridescent and surrounded by a distinct dark margin. 



Bemarks This fine large species was one of many fine shells 



