This genus (as a whole) was not to be found in the manuscript System.
Its components were distributed into three groups, two of which bore
names that were subsequently allotted to forms very remote from those
therein so designated.
CUNNUS. Testa subrotunda. Rima nymphis instructa. Dentes cardinis 4,
lateralibus divaricatis versus latera. This contained the bulk of the
_Veneres_, all except Nos. 63, 66, and those referred to _Pholas_ and
_Chama_.
PHOLAS. Testa lenticularis. Rima fissa, destituta nymphis. Dentes
cardinis 1 s. 2, marginalis tantum intra anum. _V. Pennsylvanica_,
_incrustata_, _punctata_, _edentula_, _exoleta_, _scripta_, _pectinata_,
_ziczac_ were its constituents.
CHAMA. Testa ovalis cum angulo. Cardo dentibus 4 confertis, quorum
unus in singula valvula bifidus. In this were located _V. literata,
rotundata, decussata_.