140 ON THE NAIADES, 



Unio Nicklinianus. Plate I. fig. 1. 



Testa suhtrigond, inxquilaterali, obliqud, maxime undulatu, usque ad natium 

 apices; valvulis crassissimis ; dentibus lateralibus crassis curvisque ; cardinalibus 

 maxime crassis ; margaritd albd et iridescent e. 



Shell subtriangular, inequilateral, oblique, very much undulated, even to the point 

 of the beak; valves very thick; cardinal teeth very u.ick ; lateral teeth thick and 

 curved ; nacre pearly white and iridescent. 



Hab. China. .luv 



My Cabinet. 

 Diam. 2, Length 5, Breadth 5-8 inches. 



Shell subtriangular, oblique, very much spread out, with an elevated 

 wing, flattened towards the beaks, the greatest diameter being near the 

 posterior basal margin, covered with numerous undulations, except on 

 the anterior and basal margins ; undulations diverge from the beak, and 

 are largest near the posterior margin : substance of the shell very thick 

 in the region of the basal margin ; beaks pointed but not elevated, cov- 

 ered with numerous beautiful literations to the very point ; epidermis 

 dark brown ; cardinal teeth very large, thick and sulcate ; lateral teeth 

 thick and curved ; anterior cicatrices rough and distinct ; posterior cica- 

 trices slight and confluent ; dorsal cicatrices situated on the under side 

 of the cardinal tooth ; cavity of the beaks angular ; nacre pearly white, 

 very iridescent on the posterior part, where the undulations are visible 

 from without. 



Remarks. — I met with this very interesting species in the autumn of 

 1831 at a dealer's in New York. I was informed that it was supposed 

 to be from' China. A single valve only could be obtained, and this 

 unfortunately not entirely perfect. The characters are, however, so 

 distinct from any species I have seen, that I have not hesitated to give 

 it a place among my new species. It is remarkable for its great extent 

 from the top of the wing to the basal margin, and for its numerous 

 undulations. In outline and diameter it resembles the Symphynota 

 complanata (nobis) {Masmodonta complanata of Barnes), but differs in 

 being less transverse, higher in the wing, and more thickly covered 



