OF SOUTHERN INDIA. 191 
anterior canal itself is always somewhat deepened, the columella terminating abruptly 
on it, while in Sandbergeria there is no such separate canal, and the columella 
flattens out very gradually into the shallow depression of the margin. A reference 
to Reeve’s Monograph of Cerithidea and to Deshayes’ Atlas, Pl. LX XXTI, Figs. 2, 6, 
10, 18, a.oth., will make this clear enough. We have among the Indian fossils two 
species which probably belong to the section Sandbergeria; Cer. antecedens, n. sp. 
and C. erispicans, n. sp. 
8. Fastigiella, Reeve, 1848 (H. and A. Adams, Gen. I. p. 155.), a turreted 
shell with spiral ridges, without transverse ribs, but umbilicated. 
9. Cerithium, Adanson, 1757 (H. and A. Adams’ Gen. I, p. 284). 
10. Vertagus, Klem, 1753 (ibid, p. 285). 
11. Colina, H. and A. Adams, 1853 (ibid, p. 286). 
b. Sub-family,—TRIPHORIN Z. 
Vide Triphorina, Gray’s Guide, 1857, p. 108. 
Triphoris, Deshayes, 1830 (Adams’ Gen. I, p. 287).—It is likely, that the 
sub-genus Jno, Hinds, would form a good generic distinction, and that a good 
number of the slender turreted jurassic species of Cerithiwm belong to it. They 
would appear somewhat like not perfectly developed species of Triphoris, which seems 
also to be the case with the recent shells. 
b. Sub-family,—POTAMIDIN &. 
We have already referred tosome of the more prominent distinctions of this 
sub-family, and they will be found treated more in detailin any of the newer 
Manuals. The genera are numerous, but pretty well known, and have been lately 
monographed by L. Reeve in his ‘ Conchologia Iconica.’ It is remarkable to hear 
this conchologist often saying, that it is very difficult to specify distinctly the 
characters of one or the other genus, but, when the respective species are placed 
beside each other, they are so similarly formed that nobody would hesitate a moment 
to refer the same to one genus. It is evident, that there are still some characters 
to be discovered in these shells, and that we have not as yet succeeded in pointing 
them out distinctly. 
The genera usually distinguished are: Bittiwm, Pyrenella, Tympanotonus, 
Potamides, Pyrazus, Telescopium, Cerithidea, and Lampania. 
Strictly speaking, the poramrpiv” cannot be looked upon as anything else 
than ceriraiNv®, which have been transformed and changed under somewhat 
different conditions, as the influence of the medium in which they lived, etc. They 
form in this respect a good transition to the Wezzanipz. It is nearly the same case, 
as we shall see more clearly and extensively developed in the Rissorpz. It must 
never be lost sight of, that the porauzpivz could develope themselves only where 
the necessary conditions were favorable for them. On precipitous sea-coasts, where 
