OF TIIF. FAMILY OF NAIADES. 449 



pressed; valves thick; posterior dorsal margin winged and connate; a 

 large cardinal tootli in each valve ; an irregular callous plane under the 

 ligament; beaks compressed and scarcely projecting; ligament conceal- 

 ed ; nacre white and iridescent. 



f Fox River. Mr Schoolcraft. 

 Hab. < Wisconsan. Captain Douglass. 

 £Ohio. W. Cooper. 



My Cabinet 



Cabinet of Mr Barnes. 



Cabinet of Prof. Yanuxem. 



Cabinet of the New York Lyceum. 



Cabinet of Dr Miteliill. 



Cabinet of the Academy of Natural Scienct B. 



JUasmotUmta complanuta. Barnes. 



Diam. *9 — 1-4 inches. Length from beaks to base, 3 inches. 



Breadth 5 inches. 



Length from the top of the wing, 4-3 — 4-5 inches.* 



Shell triangular-ovate, inequilateral, transversely wrinkled, 

 compressed, the largest diameter being nearly 2<9ds of the dis- 

 tance from the beaks to the base : substance of the shell thick ; 

 valves elevated into a moderately sized wing over the ligament, 

 and connate; this wing is traversed al right angles to the 

 wrinkles, by obscure undulations reaching to the beaks; beaks 

 much compressed and scarcely projecting, crowned bj seve- 

 ral double concentric undulations, which terminate in a point : 

 ligament concealed in the wing: sinus subquadrate ; epider- 

 mis dark brown and irregularly wrinkled: cardinal tooth 

 thick, elevated, sulcated, and diverging from the 1" aks : a \\ ide, 

 irregular callous plane extends under the ligament ; cicatrix s 

 in tb«' anterior margin three, and irregular; in the posterior 

 margin two, confluenl and scarcely perceptible; dorsal cica- 

 trices very perceptible; cavity of the beaks and disk small; 

 nacre while and iridescent 



Remarka. — This shell, first described by Barnes, is a rare 



9 description; my specitw in is ml h> i more '■' nb 



