Geothauma
Morphology:
Testa dextra, umhiUcata, trochiformis,. tenuis, trans-
lucida. Spira depressè ptjrainidata, apice sublœvi, obtuso.
Croose, H. (1892). "Sutura subimpressa. Anfractus 6, vix coiwexi, tertius, quartus et quintus cingulo spinarum cazarum muniti, ultimus spmis magis ac magis elongatis, incurvis, crys- tallinis, armatus, subito devians, incuroatus,juxtd spiram ascendens, mox spiram superans, rursùs lioi^izontaliter incurvatus, liber. Apertura rotundata. Peristoma duplex: internum simplex, tenue, continuum, externum haud nitens, concentricè striatum. — Operculum ?"