60 PKOCIOKniNGS OF THK jM A LACUI.OGICAL SOCIETT. 



Sub-family MERETRICIN^. 

 Genus Callista, Morcli (after Poll). 



The shells of this genus were included under Ilereirix (= Cytherea) 

 by Lamarck, but were recognized as a sub-genus by Morch in 1853, 

 and as a genus by the Adams in 1857. Having fully described this 

 group of sliells in a recent paper,' and having therein given mj- reasons 

 for attaching to it as sub-genera the recent and fossil gronps known 

 as Aphrodina , Tivelina, Transenella, and Lepidocardia, I need hardly 

 reprint all the descriptions there set forth, but shall merely give 

 a generic description and enumerate the subordinate groups. 



Type, Vennx chione, Linn, (fixed by Meek in 1876). 



Synonyms: Chione, Gray, 1838 (not Megerle) ; Dione, Gray, 1847 

 (not Hubner) ; Chionella^ Cossmann, 1886. 



Sliell oval or elongate, smooth, striate or concentrically lidged. 

 Lunule circumscribed, but escutcheon not defined. Hinge of left valve 

 with a strong anterior lateral and three cardinals, of which the two 

 anterior are united at the top, and the posterior is confluent with the 

 nymph ; in the right valve are two anterior laterals and three c;irdinals, 

 of which the two anterior are near together, llight ))Osterior margin 

 always, and left anterior margin generally, grooved, the opposite 

 margins being bevelled to fit into tliese grooves. Ventral margins 

 sniooth (except in Trmuenella). Pedal scar connected with that of 

 adductor by a long narrow canal. 



Section Callista, s.s. Type, Venus chione, Linn. 



Surface glossy and veriiicose, with minute discontinuous ingrained 

 radial striiB. Pallial sinus wide, horizontal, and pointed in front. 

 ]light posterior cardinal narrow and superficially grooved. 



Section llacrocallisia. Meek (1876). Type, V. nimbusa, Sol. 



Section Callistina, J. -Br. (1908). Tvpe, Cytherea plana, Sow. 

 (Cret.). 



Sub-genera. 



Lepidocardia, ])a]l, 1902. Type, Ve7ius africana, Phil. 



Shell small, compressed, and posteriorly attennated. Hinge short 

 and teeth crowded. 



Transenella, Dall, 1883. Type, Cytherea conradiana, Dall. 



Pallial sinus rounded Valve-margins tangentially grooved. 



Tivelina, Cossmann, 1887. Type, Cytherea tellinaria, Lam. 



Small and compressed. Cardinal teeth all short. Pallial sinus 

 smnll, rounded, and ascending (Eocene). 



Aphrodina, Conrad, 1868. Type, Merefrix tippa^ia, Conr. 



Cai'dinal teeth widely divergent. Pnllial sinus deep, ascending. 



Cretaceous and Eocene fossils. 



Genus Amiantls, Carpenter, 1865. 



Synonyms: Diane, (jray, 1847 (not 1851); Dione. Homer, 1862; 

 Dione, Fischer, 1887; i/iy.v/fd'roco?*^/?^ is pre-Linnsean. 



' Proc. Malac. Soc, vol. x, p. 335, 1913. 



