430 CRETACEOUS GASTROPODA 
this genus into Alys, Roxania, Alicula and Sao, thus admitting the last one again 
only as a sub-genus. 
9. Laona, A. Adams, 1865 (Ann. mag. nat. hist., XV, p. 324), with the 
type ZL. zonata, which is semi-ovate, thin, the striee of growth being lamellar, spire 
hidden ; aperture with the inner lip arcuated, outer lip simple. 
10? Physema, H. and A. Adams, 1857 (Gen., II, p. 21), has a globose, 
hyaline shell with the outer lip greatly dilated posteriorly, but a sharp linear inner 
lip with the columella reflected. The hyaline structure of the shell appears to 
be more that of a Pteropod than of an Opisthobranch. 
Of the other genera, referred by H. and A. Adams to the Buzzrpx, Akera 
belongs, I believe, to the Oxywozrpa”; Scaphander, Smaragdinella and Cryptoph- 
thalmus to the PurxrvEerDzZ. 
The shells of the Buzzzpx being to a large extent thin and fragile are not 
common in the fossil state, and even of those which are more solid not many 
species have been described. The oldest and at the same time most numerous 
are the species of Cylichna, beginning in the Trias; Bulla is only known from 
the Jurassies, as likewise forms agreeing with Haminea and Atys. 
The scarcity of the fossils is not unusually taken advantage of in describing 
imperfect specimens of shells, of which the proper generic characters often can 
hardly be traced out. 
The following is a list of the cretaceous species :— 
Cylichna. 
1-3. Cy. Htalloni, P. and C.; Cy. Tombeckiana, P. and Renev., ? Bulla Santonensis, VOrb. 
(vide Pictet Paléont. Suisse, 3me. Ser., p. 179). . 
4. Cy. Milleri, Bosq., in Staring’s Bodem van Nederland, IIde. deel (Bulla cretacea, Miller, 
not @Orbigny). 
5-7. Cy. Palassoui, ovoides, and Baylei, VArchiac (Bull. Soc. Géol. France, 1854, XI, 
pp. 216-217, pl. 4, figs. 1, 2, and 9). 
8. Cy. reperta, Coq. (Bulla, id., Etage Aptien de Y Espagne, 1865, p. 83, pl. 3, figs. 11-13). 
9. Cy. Chilensis, ’Orb., Voy. Astrolabe, Paléont., pl. 1, figs. 13-15. 
10. Cy. costata, Gabb, Pal. Calif., I, p. 143, pl. 21, fig. 107, has very much the appearance 
of an Atys. 
11-15. Cy. minuscula, Shum., Cy. recta, Gabb, C. scitula, M. and H., Cy. secalina and striatella 
of Shumard are quoted by Meek in his Check list of N. American cretaceous fossils, p. 16. 
16-17. Cy. Oregonensis and petrosa, Conrad, are quoted by that author in his list of eocene fossils 
(p. 9); they are marked -as occurring in the lower beds which Gabb and others maintain to be of 
cretaceous age. 
18. Cy. inermis is the only species as yet found in our South Indian cretaceous deposits. 
Volwula. 
19. Volvula dactylus, Pict. and C. (Mat. Pal. Suisse, 3me. Ser., p. 174, pl. 60, fig. 5) is the 
only species belonging to this genus. 
Actaonella. 
20-24. Acteonella levis, Sow. (imeluding Act. caucasica, Zek., and Act. obliquestriata, Stol., as 
synonyms), Act. crassa, Duj. sp., Act. glandulina, Stol., Act, faba, Kner, Act. dolium, Romer 
(vide Sitz. Akad., Wien, 1865, LIT, pp. 520-522). 
