OBSERVATIONS ON THE FAMILY CARDINIIDAE (CLASS BIVALVIA)

The composition and systematic position of the family Cardiniidaeare discussed, and the conclusion is reached that, while Cardiniaitself was an early representative of the order Heterodontida,other genera which were included in the family by Zittel, itsauthor, were unrelated forms belonging to a different order,the Naiadida. The amily Cardiniidae is, therefore, emended toinclude only Cardinia of its original members, together witha few other taxa of which Nidarica, gen.nov., is founded forthe English Liassic species Cardinia slatteri Wilson & Crick.Pseudocardinia nom. nov., proposed to replace Cardiniopsis Tornquist,1898, a homonym, is doubtfully included in the family. It ispointed out that in external morphology ome members of the Cardiniidae,including Nidarica, are remarkably like some Astartidae, andit is shown that early growth-stages of the species Cardinialaevis (Young & Bird) have been mistaken for the peciesAstarte striatosulcata Roemer. Of the other genera includedbyZittel in the Cardiniidae, the Carboniferous and Permian freshwaterbivalves are considered to belong to a distinct family, AnthracosiidaeAmalitsky, while Trigonodus is included in a new family Pachycardiidae.It is considered that the disregarded name Unionites Wissmannin Münster, 1841, should be revived to replace its juniorsubjective synonym AnoplophoraAlberti, 1864, an invalid homonym.he systematic position of this genus is discussed and its provisionalreference to the Pachycardiidae advocated. (Received 14 April 1961;