422 



MOLLUSCA 



SUB-KINGDOM VI 



79. 



Corbula (Bicorbula) gallica, Lain. 

 Calcaire Grossier ; Damery, near 

 Epernay, France. Hinge, I/]. 



amphidetic ; the chondroplwre is received into a socket of the opposite valve, not merged 

 with the valve margin ; hinge with one or two sub-umbonal projecting teeth, and rarely 



obscure traces of laterals ; the 

 A B posterior gape inconspicuous; 



siphons short, united, naked, 



wholly retractile. Trias to 



Recent. 



Corbula, Lam. (Figs. 779, 

 780). Small, ovate, rostrate, 

 very inequi valve, the right 



A, Corbula cannata, Du]. J 



Miocene; Potzleinsdorf, near valve convex, larger, with a 



prominent tooth in front of 

 the pit for the resilium, left 



valve with a flattened chondrophore, and usually a posterior tooth. Trias to 



Recent. 



Sub-genera : Erodona, Daudin (Azara, d'Orb. ; Potamomya, Sow.) Pallial sinus obsolete, 

 fluviatile. Pleistocene and Recent. JJothrocorbula, Gabb. With a lunule deeply indented 

 into the cavity of the valves. Tertiary and Recent. Corbulamella, Meek. With an anterior 

 myophore. Cretaceous. Anisothyris, Conr. (Pachydon, Gabb). Pliocene. Paramya, Conr. ; 

 Corbulomya, Nyst. Tertiary and Recent. 



Family 43. Saxicavidae. Gray. 



Shell substance as in Mya ; epidermis conspicuous; valves equal, free, rude, and often 

 irregular, more or less elongated and gaping, not fully covering the animal ; adductor 

 scars often irregular, the pallial 



line discontinuous or irregular, A 



the sinus distinct; shell margins 

 smooth; area obsolete; liga- 

 ment and resilium external, 

 parivincular, seated on strong 

 nymphs, sometimes widely ex- 

 tended ; hinge without laterals, 

 with few feeble or obsolete sub- 

 umbonal cardinals. Cretaceous 

 to Recent. 



Saxicava, Fleuriau (Gly- 

 cimeris, Schum. ; Hiatella, 

 Daudin ; Byssomya, Cuvier ; 

 Agina, Turton). Hinge eden- 

 tulous in the adult, with one 

 or two cardinals in the young, 

 boring in the softer rocks. 

 Tertiary and Recent. Sub- 

 genus Panomya, Gray (Chaen- 

 opea, Mayer). 



Panopea, Menard (Glyci- 

 meris, Lam. 1799, non Da 

 Costa), (Fig. 781). Large, 

 gaping widely behind and 

 slightly in front ; surface concentrically, or feebly sculptured ; an obscure tooth in 

 each valve. Cretaceous to Recent. 



Cyrtodaria, Daudin (Glycimeris, Lam. 1801). Solenoid with strong epidermis. 

 Pliocene and Recent. 



FIG. 781. 



I'tni ojifM Mcnardi, Desh. Miocene; Vienna Basin. A, Dorsal 

 view of valves. B, Internal cast. C, Hinge plate seen from above, 1/2- 



