Fam. 10. Stenogyridae.—Radula, p. 234; shell long, spiral, shining, more or less translucid, apex blunt, sometimes decollated. Eocene——. Genera: Stenogyra (subg. Rumina, Obeliscus, Opeas, Melaniella, Spiraxis, Leptinaria, Nothus, Subulina, Glessula), Ferussacia (subg. Cionella, Azeca), Caecilianella (subg. Geostilbia). Achatina (shell large, ventricose, columella strongly truncate), with the sub-genera Perideris, Limicolaria, Columna, Pseudachatina, Homorus, probably belongs to a distinct family.

Fam. 11. Achatinellidae.—Radula, p. 234; shell small, bulimoid, indifferently dextral or sinistral. Genera: Achatinella (subg. Auriculella, Amastra, Carelia), Tornatellina.

Fam. 12. Succineidae.—Radula, p. 234; lower pair of tentacles wanting or small; shell internal or external, thin, spiral or not, last whorl large. Eocene——. Genera: Succinea, Homalonyx, Hyalimax, (?) Lithotis, (?) Catinella.

Fam. 13. Janellidae.—Radula, p. 234; animal slug-like, no lower tentacles, shell an internal plate. Single genus, Janella (= Athoracophorus), with subg. Aneitea.

Fam. 14. Vaginulidae.—Radula, p. 234; animal slug-like, covered with a coriaceous mantle, lower tentacles bifid, genital orifices widely separated, male behind the lower right tentacle, female on inferior median part of right side, anus and pulmonary orifice nearly terminal; shell absent. Single genus, Vaginula (= Veronicella).

Fam. 15. Onchidiidae.—Body oval, mantle thick, often warty, sometimes set with “eyes” (p. 187), two tentacles, genital orifices widely separate, anus and pulmonary orifice as in Vaginula; no shell. Genera: Peronia, Onchidium, Onchidiella. The family appears to be an instance of Pulmonata reverting to marine habits of life.