The extinct Nerineoidea and Acteonelloidea (Heterobranchia, Gastropoda): a palaeobiological approach Author Kollmann, Heinz A. text Geodiversitas 2014 2014-09-26 36 3 349 383 http://dx.doi.org/10.5252/g2014n3a2 journal article 6397 10.5252/g2014n3a2 5dd903f5-b398-4a17-83e5-364766291411 1638-9395 4538503 Family PTYGMATIDIDAE Pchelintsev, 1960 ( Fig. 3 A-I) Ptygmatisidae Pchelintsev, 1960: 51 . Ptygmatisinae Pchelintsev, 1960: 51 . INCLUDED SUBFAMILIES. — Ptygmatidinae Pchelintsev, 1960 , Umboneinae Lyssenko & Aliev, 1987 and Cryptoplocinae Pchelintsev, 1960 (see Kollmann & Peza 1997 a). FAMILY CHARACTERS . — Whorls rhombic to triangular in cross section with siphonal notch. Columella hollow to solid. Two columellar plaits extending to detached columellar inductura. Parietal and palatal plait developing inside last whorl, thin and protruding strongly into the whorl interior. External end of plaits inflated, truncated or bifurcate in earlier whorls, incisions between columellar plaits deep and bent.