OF SOUTHERN INDIA. 211 
changes in the form and ornamentation of the shell we can only account by 
the supposition, that the individuals were living in brackish-, or partially even in 
fresh-waters. Save in the porammpinm or the Mezanupa such remarkable varia- 
tions in one and the same species are scarcely to be found in any other group. 
Thus the mode of life can render a character, which is sometimes very important in 
a classificatory point of view, under other circumstances almost valueless in that 
respect. We gladly concede, that the general form of the shells and especially that 
of the whorls with their spirally arranged ornamentations appears fully to justify 
the classification of Glauconia in the family Yurrirerzm.s, but at the same 
time the massive structure of these conical shells and the anterior insinuation, or 
emargination of the aperture, are so far characteristic, as to make a generic separa- 
tion of those shells very desirable. 
I have already in my revision of the Gosau-Gastropoda advocated the idea, 
that most of the species of Glauconia appear to be inhabitants of brackish— or 
fresh-water. I may also refer to the similarity in the structure of the shells and the 
form of the aperture between Glauconia and Lampania or Ceriphasia of the 
Meztanip#. In this respect our genus may be regarded as a truly intermediate form 
between this last named family and the Tvrrrrezzi.s#, for it may almost with 
the same reason be supposed to belong to the former. 
The oldest known representative of Glauconia is described by Dunker 
from the Wealden deposits of Northern Germany under the name of Welania,- 
having been previously reported as Melanopsis or Potamides,- namely, Melania 
strombiformis, Schlot. sp. (Wealden Monograph, p. 50, pl. 10, figs. 17-19 and 
24). Of the other species noted in the same work the generic determination 
is somewhat doubtful; some of them may belong to Glauconia, others to Can- 
thidomus (from which Lyrcea is scarcely different), or Fawius, and a few appear to 
be true Melanie. . 
In the cretaceous deposits three different horizons of Glauconia are at present 
known. The first are those described by Coquand in his Monog. of the ‘ Etage 
Aptien’ (Marseille, 1866), namely, Glau. Pizcuetana (Pleurotomaria? id., Vilanova, 
Mem. R. Acad., Madrid, 1859, Vol. IV., pl. 2, fig. 12,—Cassiope. id. et Tekelit, 
Coquand, loc. cit., p. 58, pl. 3, figs. 1-3), a species much resembling the senonien 
Glau. Renauxiana, D’Orb.; Glau. (Cassiope) turrita, Coq. (1. cit., p. 60, pl. 3, 
figs. 5-6), which is probably not specifically different from Glau. helvetica, Pictet 
et Renevier; Glau. LInjani, (Cerith. id. Verneuil,— Cerith. Lusani apud Vilanova,— 
Cerith. Heeri, Pictet et Renev.,— Cassiope Verneuili et Lujani, Coquand, 1. cit., pl. 4, 
figs. 1—5), is closely allied to the last species; and Glaw. (Cassiope) Renevieri, 
Coquand (ibid., fig. 8), which is very likely not different from Glaw. Pizcuetana. 
The second horizon of Glauconia is in the Cenomanien. Prof. Hebert, 
whose instructive collections in Paris I had lately an opportunity of examining, 
showed me a fine series of three or four new species from these beds, but the names 
and descriptions of these species are not yet published. 
