CLARS I 



PELECYP0DA 



471 



This family, so well known under the preoccupied nanie Cyprinidae, probably shared the 

 same origin as the Astartidae, and tlie two do not definitely separate until the Jura. The 

 Position of the Paleozoic ancestors is neeessarily doubtful, and they are placed ditferently 

 by different authors. The group i.s divided into two subfaniilies, Pleurophorinae and 

 Vetiiellinae. 



.Pleurophorus King (Fig. 749). Elongated, siib-rectangular ; beaks sub-terminal ; 

 surface smootli or witli radial sculpture ; hinge with two cardinal teeth in each valve ; 



Pleurophorns costatu!^ King. Per- 

 mian ; Byers Quarry, England. A, 

 Shell, Vi Gifter King), ß, Internal 

 mould Ironi Gera, Tlniringia (after 

 Geinitz). 



Anisrimrdia elegans Mun.-Chalra. Kimmeridgian 

 Cap de la Heve, near Havre i/i> 



anterior adductor scars deep, with a buttress-like ridge behind it. Devonian to 

 Trias ; especially abimdant in the Permian, 



Cypricardella Hall {Microdon Hall); Mecynodon Keferst.; Gypricardinia Hall. 

 Devonian. Astartella Hall. Carboniferous. 



Änisocardia Mun.-Chalni. (Fig. 750). 



Rounded or trapezoid, plump, smooth or 

 radially striate ; posterior slope some- 

 tinies keeled ; hinge with a strong 

 sometinies bifid right cardinal behind, 

 and an anteriorly directed front cardinal; 



Venilicardia cordiformis, d'Orb. 

 Gault ; Seignelay, Yonne. 



Fi(i. 753. 

 Veniella tumida Nyst. Crag ; Antwerp. 



left valve with a forwardly directed anterior and a posterior cardinal tooth. Jura to 

 Tertiary. 



Boudairia Munier-Chalm. Like Trapeziim, but with a sharp keel and smooth 

 area behind, anteriorly with concentric ridges ; right posterior cardinal bifid. Upper 



Cretaceous. 



