SS I PELECYPODA 473 



02ns Defr. (Fig. 758). Trigoiial, cordate, sinootli or coiMcutricnlly sliialc; beaks 



Fig. 757. 



Astarte (Goodallia) 

 milinris Defr. Eocene ; 

 Grignon, near Paris 

 (after Desliayes). 



Fig. 755. 



Astartc ohllqua Desh. Inferior 

 Ooiite ; Bayeux, Calvados. 



Fig. 756. 



Digitari profunda Desh. 

 (as Woodia). Eocene ; Aizy, 

 near Laon. A, Hinge, en- 

 larged. B, Shell. 



2)ronii]ieiit, prosocoelous ; limule very deep, bordered by a keel ; 

 cardinal teetli long, iiarrow (2 : 1). Trias to Cretaceous. 



Fig. 758. 



Opis goldfussiana 



Opisoma Stol. Jura. Seehachia Neiiniayr. Cretaceous. theim*. Würtemberg.^ 



Family 5. Crassatellitidae Dali. 



Shell as in thr, Ädartidae, hut the valves always somewhat unequal, and nsualhj 

 Diore or less radrufi', fhe heaks compressed, erect or opisthocoelous ; liyanient infernal, 



CrassatelUtcs plumlmi (Chem.). 



Fig. 750. 

 Eocene (Calcaire Grossier) ; Damery, near Epernay. 2/3. 



more or less obsolete, resilium large, wholly internal, attached at each end to a chondro- 

 phoric pit in the hinge plate behind the cardinal teeth ; lateral teeth and sockets usually 

 alternated in the valves, the hinge plate heavy, flat ; the posterior cardinal in the right 

 valve very small or obsolete, lüith no distinct socket in the opposite valve ; füll cardinal 



formula 



L 1010 

 RIOIUI' 



Lower Cretaceous to Kecent. 



Tlie earlicr foriiis of tliis fiiniily liave a sniall resilium close to the nearly ni.iVL^iiial ülj.-i- 

 ment. Witli iimc. Liter oin's show ;i gradual descent of tliese organs, until in sninc of \\\v 

 niorc spoeialiscd iiioilcni n|ii('sriitati\-es tliere is no approciable liganient rciiiainiiiLr. and tlie 



