CLASS I 



PELECYPODA 



489 



Kelliella Sars ; Lutetia Desli. ; (?) Ällopagus Stol. ; Turtonia Alder. 

 Receiit. 



C Cyclodonta. 



Eocene to 



Teeth arched, sprmging from helow the hinge margin, with the hinge-plate ohscure or 

 absent. 



Superfamily 9. CARDIACEA Lamarck. 



Lobes of the mantle free behind the siphons, foot elongate, geniculate ; sculpture of 

 the shell chiefly radial ; cardinal teeth conical, the lateral laminae short, distant from the 

 cardinals. 



Family 26. Cardiidae Fischer. 



Shell substance cellulo-crystalline, with the external layer more or less tubulär ; valves 

 equal, free, gaping slightly behind, the beahs prosocoelous, the margins usually serrate or 

 radially striated ; adductor scars sub-equal, the pedal distinct and usually distant; 

 ligament and resilium parivincular, external, short, set in a groove ; area obscure ; com- 

 plete hinge armature consisting of an anterior and posterior lateral in the left, and two 



B 



Fio. 801. 

 Cardium %irodiLctum Sow. Turonian ; St. Gilgen, Salzburg, i/i- 



anterior and one posterior lateral in the right valve, any or all of which may be absent ; 

 cardinal formula üöfQi > ^^^^ ^ß^^^^ simple, smooth, never bifid, one cardinal in each valve 

 usually persistent, the others inconstant. Trias to Recent. 



Cardium Linii. (Figs. 801-803). Cordate, iiiflated, radiately ribhed or .striated, 



Fio. 802. 



Protocardia hifrons 

 Reuss. Turonian; 

 Strobl- Weissenbach am 

 Wolfgangsee, Austria. 



Vi- 



Fio. 803. 



Cardium (Discors) discrejxins Bast. Miocene 

 Dax, ne.'ir Bordeaux, '/i. 



