910 PELECYPODA. [EulamelHbranchia. 



and centrally located between the valves. The prodissoconch in this 

 group is of the usual size, but appears very prominent on account of 

 the relatively small additions made to it in growth. As in Cardita. 

 the margins have sometimes a projecting border externally, which 

 under magnification appears quite prominent, but in the larger forms 

 now added to the family is not especially noticeable. (Dall.) 



The family comprises now the following genera : Erycinclla, 

 Conrad, 1845 ; Carditella, E. A. Smith, 1881 ; Carditopsis, E. A. Smith, 

 1881 ; Condylocardia, Bernard, 1897. 



Eocene to Recent. 



Genus 1. CONDYLOCARDIA, Bernard, 1897. 



Condylocardia, Bernard, J. de Conch., xliv, 1896 (1897), 174. Type : 

 C. Pauliana, Bernard. Condylocardia, Dall, Proc. Acad. N. Sci. Philad., 

 1902, 702 ; Trans. Wagn. Free Inst., iii, pt. 6, 1437. 



Shell small, globose, equivalve, more or less inequilateral and 

 produced in front. Beaks prominent, with an umbonal cavity which 

 is formed by the embryonic shell, whose apex is rounded. Cardinal 

 margin straight, short, formed exclusively by the cardinal margin of 

 the embryonic shell. Hinge-plate well developed, covering the um- 

 bonal cavity. Anterior and posterior ends almost straight or curved, 

 ventral margin regularly convex. Shell-substance compact, without 

 nacreous or prismatic layer. Ligament internal, submedian, a little 

 behind the middle. In the right valve the anterior margin of the 

 shell is reflexed near the hinge-plate, and forms a hook which con- 

 stitutes 2 cardinal teeth. Posteriorly there is the same disposition, 

 but the teeth are more dorsal and rudimentary. There is an anterior 

 lateral tooth, distant from the apex. Left valve with a prominent 

 cardinal tooth on each side, continuous with a crest following the 

 margin of the valve, which, becoming detached, forms a lamellar 

 posterior lateral tooth. There are 2 subequal adductor-scars beneath 

 the lateral teeth. Pallial line simple. 



Distribution. Islands of St. Paul and St. Helena, New Zealand. 

 Australia, Tasmania. 



Fossil in the Parisian Eocene. 



KEY TO SPECIES. 



A. Shell concentrically ribbed . . . . concentric^. 



B. Shell radially ribbed . . crassicostu. 



1. Condylocardia concentrica, Bernard, 1897. Plate 53, fig. 5. 



Condijlot-itrditi concentrica, Bernard, J. de Conch., xliv, 189t> (1897), 17i>, 

 pi. (i, f. 2 ; 180, f. 2 in text ; 203, f. 5 (2) in text. 



Shell minute, inequilateral, with prominent prodissoconch, con- 

 centrically ribbed. Beaks approximate, very conspicuous, prodisso- 

 conch with a broad projecting rim. A ulcrior end produced, descending, 

 straight, subangled on meeting the convex basal margin : posterior 



