440 NEW GENUS AND SOME NEW SPECIES 



11. Unio Zig-zag. Plate XII. fig. 19. 



Testa ovatd, incBquilaterali, ventricosd ; valvulis sub-crassis ; dentibus 

 cardinalibus magnis, erectis ; lateralibus curvatis; natibus prominulis; 

 radiis ex lineis angulatis compositis ; ligamento brevi ci'assoque ; marga- 

 rita alba. 



Shell ovate, inequilateral, ventricose ; valves rather thick; cardinal 

 teeth large, erect ; lateral teeth curved; beaks rather prominent; rays 

 composed of zig-zag lines ; ligament short and thick ; nacre pearly white. 



Hab. Ohio. T. G. Lea. 



My Cabinet. 

 Cabinet of T. G. Lea. 

 Cabinet of Prof. Vaniixem. 

 Cabinet of P. H. Nicklin. 

 Cabinet of the Academy of Natural Sciences. 

 Cabinet of Peale's Museum. 

 Diam. '6, Length -9, Breadth 1-5 inches. 



Shell ovate, inequilateral, ventricose ; substance of the shell 

 thick ; beaks rather prominent, subcarinate posteriorly, gene- 

 rally eroded ; ligament short and thick ; epidermis yellow in 

 ground, but traversed by oblique green rays, v^^hich give it 

 sometimes a dark hue ; these rays pass from the beaks to the 

 margin over, the whole disk, and are formed by zig-zag lines, 

 which in some specimens are joined so closely as to become 

 confluent ; on the posterior slope are irregular lines converging 

 below the ligament; cardinal teeth large, deeply divided in 

 the left valve ; lateral teeth slightly curved ; anterior cica- 

 trices distinct, as are also the posterior, the smaller of which 

 is placed against the side of the lateral tooth at its termina- 

 tion ; dorsal cicatrices situated along the base of the cardinal 

 tooth within the cavity of the beaks ; cavity of the beaks 

 shallow ; nacre pearly white and iridescent. 



Remarks. — This beautiful little shell is about the size of 

 Barnes's jsarwMs. It is however entirely distinct from it. It 

 is much heavier, more ovate, and radiated ; has no concentric 

 undulations at the beaks like the parvus, which character Mr 



