CONCHIFERA. 



Crags of England, in that of Anvers, and in tlie Pleistocene 

 deposits of Palermo. 



Fossil, 8 species. Eocene, Miocene, Pliocene. France, 

 England, Germany. W. lamellosa, Sandb., is inequilateral. 



LxTTETiA, Deshayes, 1860. 



Example, L. Parisiensis, Deshayes. 



Shell small, orbicular, globose, equiyalve ; valves closed ; 

 border simple and entire ; binge narrow ; cardinal teetb three in 

 each valve, two diverging ; the third large and obliquely placed 

 between the others ; muscular scars small, oval, submarginal, 

 equal ; pallial line simple ; ligament external. 



Fossil, 2 species. Eocene. Paris. 



GooDALLiA, Deshayes, 1860. 



Example, Erycina miliaris, Defrance. 



Shell small, trigon al, equivalve, inequilateral ; valves closed ; 

 cardinal teeth in the right valve two, diverging, separated by a 

 triangular socket ; in the left valve, one triangular, sometimes 

 bifid ; lateral wanting, or rudimentary ; ligament external, very 

 short ; pallial line simple. 



Fossil, 8 species. Eocene. Paris. 



GooDAiiLiopsis, Eaincourt and Munier, 1863. 



2'ype, G. Orbignyi, Eainc. and Mun. Eocene. Eercourt. 



Shell oval, flattened, equivalve, inequilateral, smooth, slightly 

 dilated in front, and compressed behind ; valves closed ; hinge 

 with two cardinal teeth, separated by a triangular socket, in 

 each valve ; lateral teeth distinct and elongated, one in eaclj 

 valve. Other characters those of Goodallia. 



EAMILY SIV. — ^YE^T:RLDiE.* 



PsATHUHA, Deshayes, 1860 (see p. 456). 



Etymology , xpaQvpbg, friable. 



Type, Erycina fragilis, Lamk. Eocene. Paris basin. 



Shell oval, inequilateral, thin, transparent, fragile; hinge 

 teeth, in the right valve, two equal and deeply bifid ; left valve, 

 two unequal, entire ; ligament external ; anterior adductor scar 

 narrow, claviform ; posterior subquadrangular ; pallial simple, 

 thus differing from dementia, to which it is related by the hinge 

 characters. 



* See p. 473. 



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