ORDER III 



TELEODESMACEA 



1 1 r, 



Family 31. Veneridae. Leach. 



Valves equal, free, closed, with prosogyrous beaks, variably sculptured, will th< 

 margins more or less dentate, except in the smooth species; adductor scars peripheral, 

 pedal distant ; pallial sinus more or less sinuated, area very distinct ; resilium usually 

 external, embraced by the ligament; hinge plate developed; formula of the car* I ///./.< 



kl^ 1010 , with a single obsolete lateral in one valve; the cardinal* frequently //;//, 



R010101 



usually radially disposed and sub-equal in size, except the posterior left one, which is often 



obsolete or obscure; supplementary cardinals or 



rugosities are present in specialised forms. Jura 



to Recent ; maximum in Tertiary and later. 



The family must be divided into at least four 

 sub- families, as follows : 



a. Vencrinac : typical, with produced siphons, 

 not byssiferous, the young not retained within the 

 mother after leaving the egg. 



b. Circinae : with separate short siphons, correla- 

 tive nearly simple parallel line, sub - internal, 

 partially amphidetic resilium, and compressed beaks. 



c. Tapetinae : with long but partly separated 

 siphons, a byssus present at least in the young ; 

 hinge with no lateral teeth, otherwise like the 

 Venerinae. 



d. Gcmminae: minute shells, with more or less 

 separated siphons, no byssus, obsolete lateral laminae, 

 and sheltering the nepionic young within the cavity 

 of the mother. 



a. Pronoella, Fisch. (Pronoe, Ag. non Guer. 

 Me"n.) Compressed, pallial sinus very shallow ; 



I i ., i iii j- i i Cvpriiiie.riit i/ixci/x, Mutli. .sp. L'IMMT Cn- 



a posterior lateral and three cardinals in each tac eo lis ; Oosau Vaii.-y, Austria. 



valve. Jura. 



Cyprimeria, Conr. (Fig. 758). Like the preceding, but the right valve with only 



two cardinals, the hinder one bifid ; pallial sinus very shallow. Cretaceous. 



Dosinia, Scop. (Artemis, auct.) Orbicular, lentiform, concentrically sculptured, 



with a deep, well-marked 

 limule; cardinals 3:3; pallial 

 sinus deep, ascending, pointed. 

 Cretaceous to Recent. 



Cyclina, Desli. Cretaceous 

 to Recent. Sunetta, Link 

 (Meroe, Sclmni.) ; Grateloupia> 

 Desm. Tertiary and Recent. 

 Venus, Linn. (Fig. 759). 

 Oval or rounded, plump,, 

 cordate, thick ; concentrically 

 or radially sculptured, with 

 denticulate margins ; hinge 

 plate broad, with three 



cardinals in each valve and no lateral teeth; pallial sinus short, angular. Jura 



to Recent; represented by about 200 fossil and as many recent species. Very 



numerous sub-divisions have been proposed ; Venus s. s. is typified by V. mercenaria, 



Lam. 



Meretrix, Lam. (Cytherea, auct.), (Figs. 760, 761). Hinge with lateral teeth. 



Tertiary and Recent. 



Fit;. 759. 

 Venus cincta, Eichw. Miocene ; Gainfahrn, near Vienna. 



