90 Marine Shells of the Western Coast of Florida 



glossy, transparent epidermis; inequilateral, anterior portion broadly 

 rounded, posterior portion demarcated by a cordlike radial rib; 

 margin reflected and gaping; umbos high, directed backward; sculp- 

 ture of delicate, irregular, elevated concentric ridges; teeth and 

 fossette are typical. 



Subgenus KAETA Gray, 1853 

 Anatina plioatelbli'^'S (Lamarck) [A. canallculata (Say)] PI. 18, fig. 117 



Alt., 68; length, 70 mm. Shell cordiform, thin, white, inequi- 

 lateral, obliquely prolonged forward; umbos high, inflated, directed 

 backward; posterior margin sinuous and gaping; sculpture of evenly 

 spaced, rounded concentric ribs, fine striations in intercostal spaces 

 and delicate, irregular radial etching; hinge typical; interior white, 

 smooth; pallial sinus deep, narrow and reflected downward at tip. 



Family tORBULIDAE 



Members of the Corbulidae are widely distributed in most of 

 the temperate seas and through a considerable range in depth. 



The shells are small, trigonal, white with brownish epidermis. 

 Subequilateral, posterior portion longer, narrow and rostrate. Ex- 

 tremely inequivalve, the right valve is usually both larger and deeper 

 and more or less overlaps the free margin of the left valve. The umbos 

 are high, inflated, anterior to the middle of the shell and directed 

 backward. The right umbo generally higher than the left. The 

 surface of the valves is concentrically ribbed. Right valve has one 

 prominent, curved, cardinal tooth and a socket for its reception in 

 opposite valve. The interior is chalky white, with two muscular im- 

 pressions, and a slightly sinuated pallial line. 



Genus CORBULA Bruguiere, 1797 

 Corbula contraetai'^a Say PI. IS, fig. 118 



Alt., 5; length, 9; diam., 6.25 mm. Anterior border short and 

 rounded; posterior extremity rostrate, narrow and bluntly pomted; 

 ventral margins contracted with concave sinuosity near center; 

 surface ribbing of elevated threads separated by wider interspaces, 



'■'■'^ Lat., plicati'lla, little folds; canalicutatus, channeled. 

 ^''8 Lat., corbula, little basket; contractus, drawn together. 



