444 NEW GENUS AND SOME NEW SPECIES 



a la carene de leur corselet ?" Indeed the fact can scarcely be 

 doubted. 



SPECIES. 



1. Svmpiiynota Ljevissima. Plate XIII. fig. 23. 



Testa ovato-triangulari, incequilaterali, transversim rugosd, sub-ven- 

 tricosa; valvulis tenuissimis, superne bi-alatis, ante et post nates conna- 

 tisque ; dcntibus cardinalibus et lateralibus lineam curvatam facienti- 

 bus ; natibus prominulis ; ligamento celato ; margaritd purpurea et 

 iridescente. 



Shell triangular-ovate, inequilateral, transversely wrinkled, sub-ven- 

 tricose; valves very thin, elevated into two wings, connate anteriorly and 

 posteriorly to the beaks ; cardinal and lateral teeth form a curve line ; 

 beaks scarcely prominent ; ligament concealed ; nacre purple and irides- 

 cent. 



Hab. Ohio. T. G. Lea. 



My Cabinet. 



Cabinet of T. G. Lea. 



Cabinet of Prof. Vanuxem. 



Cabinet of P. H. Nicklin. 



Diam. 1*4 inch. Length from beaks to base, 2-4 inches. 



Breadth 4-5 inches. 



Length from the top of the wing to base, 3-1 inches. 



Shell sub-triangular-ovate, inequilateral, sub-ventricosc, 

 transversely and very finely wrinkled, shining: substance of 

 the shell thin, but compact ; valves elevated into two wings, 

 neither of them very high, the posterior one larger than the 

 anterior, both connate ; beaks scarcely prominent, termina- 

 tion pointed, and when not decorticated exhibit two or three 

 very minute elevations, almost requiring a microscope to dis- 

 cover them ; the purple nacre shows through the epidermis 

 here, and gives the tips that colour ; ligament concealed in the 

 wing ; sinus subquadrate ; epidermis thin and purple brown ; 

 young specimens sometimes possess obscure brown rajs ; car- 

 dinal tooth lamelliform, single in the lift valve and disposed to 



