OF SOUTHERN INDIA. 275 
thickened. (List of species of Onoba vide Ann. Mag. Nat. Hist., 1861, VITIT, 
p. 299, and 1863, XI, p. 348). 
9. Diastoma, Deshayes, 1848, (Traité de Conch., p. 46, pl. 74, figs. 8-9, Paris 
foss., 2nd edit., II, p. 411). Shell turreted, whorls with numerous transverse ribs, 
and with a few intermediate varices. Inner margin of the aperture partially 
detached from the previous whorl; the aperture itself is strongly contracted poste- 
riorly. As yet only known fossil in tertiary deposits. 
10. Ampithalmus, Carpenter, 1865, (Ann. Mag. Nat. Hist., XV, p. 181), 
appears to be a somewhat similar form, but with a shorter spire. The species 
are recent, (vide also H. Adams in Proce. Zool. Soc., Lond., 1865, p. 754). 
11. Jravadia, Blanford, 1867 (Journ. As. Soc., Bengal, pt. I, p. 56, pl. 13, 
figs. 18-14) is founded upon a species, J. ornata, which was found under stones 
in one of the creeks of the Irawadi-delta. The shell has the general form of a 
Rissoa, but the apex is often obtuse, the whorls are spirally ribbed, covered with 
an epidermis; aperture ovate with continuous margins, anteriorly slightly effuse ; 
the outer lip with an external varix. Operculum and animal are unknown. 
Schwartz von Mohrenstern in his Monograph of Rissoa does not mention a 
single species with spiral ribbings, and under Rissoina only one species, the R. sulci- 
Jera, Troschel (Denksch. Akad., Wien, 1861, XIX, pt. II, p. 182, pl. 10, fig. 88). 
A similar species has been found in loose sand brought from the Arakan Coast, 
though unfortunately the unique specimen is not better preserved, than the one 
described by Troschel. From a quantity of sand, picked up by Mr. 8. Kurz on the 
shore of Termoclee (one of the Andaman Islands), I obtained another species which 
is very like the Zravadia ornata of Blanford, but the spiral ribbings are three on 
each whorl and somewhat thinner than in that species, the apex is not decollated, 
and the surface apparently without epidermis and of a pure white, like Rissoe 
generally are. Iam, however, informed by Mr. G. Nevill that the same, or a very 
similar species, is found in brackish water on the southern coast of Ceylon, and has 
when alive a brown epidermis. It is therefore a true Lravadia. 
12. Alvania, Risso, 1826, (H. and A. Adams’ Gen., I, p. 330). 
13. Rissoa, Frémenville, 1814, (¢bid. p. 329, vide postea p. 277). 
14. Scaliola, Adams, 1860, (Ann. Mag. Nat. Hist., VI, p. 120), an elongated, 
smooth, Twrbonilla—like shell; the animal is, however, stated to possess a rostrum, 
like the Rissormm. A fossil species was described by Semper, Sc. Mohrensterni, 
from the oligocene beds near Latdorf, (vide Journ. Conch., 1865, V, p. 432). 
15. WMicrostelma, Adams, 1863, (Ann. Mag. Nat. Hist., XI, p. 347), has been 
proposed for another shell like a Réssoina, or rather Turbonilla, with the aperture some- 
what produced in front; the outer lip is simple, and the whorls transversally ribbed. 
A. Adams describes a recent species from Japan, I. dedala, and Semper refers a 
tertiary fossil species to this genus, 2. Bellardii (Journ. Conch., 1865, V, p. 434). 
16. Pterostoma, Deshayes, 1864, (Paris foss., 2d. edit., II, p. 428,) has been 
proposed for turreted Rissoina—like shells with the margins of the aperture much 
expanded. There is only one species known from the Paris basin, and described 
