CHAMIDiE. 191 



The curious history of the genera of this famil}^, and of the 

 many conflicting views of their extent and relationships, is ably 

 given by Prof Angelo Heilprin in Proc. Acad. Nat. Sciences, 

 Philad., 423, 1881. 



Verticordia, Searles Wood, 1844. 



Etym — Verticordia, a name of Venus. 



8yn. — Trigonulina, d'Orb. 



Distr. — 3 sp. China Sea, Mediterranean ? Fossil, 2 sp. Mio- 

 cene — ; Britain, Sicil}^, North Carolina. V. cardiiformis^Wood 

 (cxxv, 26). 



Shell suborbicular, with radiating ribs ; beaks subspiral ; mar- 

 gins denticulated ; interior brilliantly pearly ; hinge with one 

 prominent cardinal tooth in each valve ; adductor scars two, 

 faint ; pallial line simple ; ligament internal, oblique ; epidermis 

 dark brown. 



Pecghiola, Meneghini, 1851. 



Distr. — 3 sp. N. Europe. F. argentea^ Meneg. Miocene; 

 Europe. 



Shell suborbicular, equivalve, strongly ventricose, with the 

 beaks incurved and distant from each other, surface radiately 

 sulcated and ribbed ; hinge in the right valve with a strong car- 

 dinal tooth below the umbo, a corresponding indentation in the 

 left valve ; ligament apparently linear, situated along the upper 

 posterior margin. 



Allopagus, Stoliczka, 1870. 



Syn. — Hippagus, Desha3^es, non Lea. 



Distr. — Hippagus Leanus, Deshaj^es (cxxvii, 60 . Paris Basin. 



Shell ovate, thin, very inequilateral, moderately tumid, with 

 small approximate beaks ; surface smooth wath simple striae of 

 increase ; right valve with one tooth in front of the umbo, left 

 with a similar tooth below the umbo ; ligament subinternal, pos- 

 terior. 



The type of this group is Hippagus Leanus, Deshayes. The 

 species differs by the hinge and the structure of its shell from 

 Hippagus, Lea's original figure of H. isocardoides being appar- 

 ently quite correct — the latter group belonging to all appearances 

 close to Mysia in the Ungulinidse. Deshayes' species is exter- 

 nally very like a Mytilimeria, but this again accords in the char- 

 acter of its hinge with true Hippagus. 



( Chamacea.) 

 Family CHAMIDJE. 



Shell inequi valve, thick, attached ; beaks subspiral; ligament 

 external ; hinge-teeth two in one valve, one in the other; adductor 

 impressions large, reticulated ; pallial line simple. 



