TRANSACTIONS OF WAGNER 



I 504 



TERTIARY FAUNA OF FLORIDA 



and free ; in the left valve a small, obscure denticle in front of the fossette ; 

 the rostrum short and pointed, the surface feebly concentrically striated. 



Subgenus Bowdenia Dall, 1903. Type C. distira Dall. 



Sculpture like Cardiomya; hinge with a posterior left and anterior right 

 cardinal, the resilium between them, but no laterals ; the margins of the right 

 valve grooved to receive the edges of the valve opposite. 



Subgenus Vulcanomya Dall, 1886. Type V. Smithii Dall, = Necsra adunca 

 Smith, not Gould. 



Surface concentrically sculptured ; hinge with no cardinal teeth, a small, 

 thickish anterior and posterior lateral in the right valve and a similar anterior 

 lateral (only) in the left valve, with a small, central fossette. 



Subgenus Luzonia Dall and Smith, 1889. Type Neara philippinensis Hinds, 

 not A. Adams. 



Surface concentrically striated ; hinge without laterals or left cardinals ; 

 right valve with an anterior cardinal, the fossette narrow, parallel with the 

 cardinal margin under the apex. 



Subgenus Plectodon Carpenter, 1864. Type P. scaber Carpenter. 



Surface granular, as in Poromya; hinge as in Leiomya, but having a tooth- 

 like prominence (rather than a real tooth) upon the margin, formed by the 

 spiral twisting under the beaks of the hinge-margin itself, upon and over which 

 in P. scaber there is a nearly obsolete external ligament ; the resilium is in- 

 serted behind and under the beaks rather than in a projecting fossette or on 

 the hinge-margin ; the tips of the siphons protected by a leathery ring, flattened 

 and broadened at the sides, analogous to the siphonal shields of Tresus. 



Subgenus Rhinoclama Dall and Smith, 1886. Type Necera philippinensis A. 

 Adams, not Hinds. Rhinomya A. Adams, not Robineau Desvoidy, is 

 synonymous. 



Resembling Plectodon, but without cardinal teeth and the surface concen- 

 trically striate without granules. 



Subgenus Tropidomya Dall and Smith, 1886. Type Necera abbreviata Forbes. 

 Tropidophora Jeffreys, not Troschel or Thompson, is synonymous. 



Surface and resilium as in Leiomya; no lateral teeth, but an anterior car- 

 dinal in each valve. 



