336 CRETACEOUS GASTROPODA 
from the Gosau; the Ner. rugosissima, Forbes, from India and others, which I have 
had the opportunity of examining, there cannot be the least doubt that they are — 
generally speaking —true Nerite, and that the occasional want of the inner lip 
and of the callosity of the shell is to be attributed to the causes mentioned 
above. 
Now comparing with these data d’Archiac’s figures of the four other species 
of Otostoma, two of which are eocene, I cannot help thinking that they are 
nothing more than incomplete specimens of Nerite, in which the inner layer 
of the shell with the entire callosity of the inner lip has disappeared. It is not 
impossible that such shells, as Vise. d’Archiac wished to refer to his Otostoma, may 
have existed; but after the numerous and repeated observations which I have made 
on the previously named species* I cannot but doubt their real existence. Still I 
do not wish to go beyond actual observation of facts, and I leave the decision, as 
to the other four species of the so-called Otostoma (as well as the two described 
by Coquand from Algiers) to any one who may have an opportunity of examining 
the original specimens. When lately myself at Paris, I felt very sorry that I could 
not during the short time of my stay succeed in obtaining access to the specimens 
which were collected by Mr. Tchihatcheff. 
There is only one point to which I would wish to direct attention. Comparing 
the species, which I will mention subsequently under the numbers 9-25, there may 
be observed in all of them a remarkable similarity in ornamentation,—consisting of 
transverse ribs on the posterior and a spiral sulcation on the anterior half of 
the last whorl—, in the great thickness of the shell and in the large size of the 
inner lip, which is smooth, reaching very low down in the space of the aperture, 
and having on its margin generally a number of eight equally strong teeth. The 
recent Verite have usually a narrower and less precipitous inner lip and a smaller 
number of teeth. Thus it is still possible that, mutatis mutandis, Otostoma 
may appear among the sub-generic divisions of Nerita. 
5. Deianira, Stoliczka, 1860 (Sitzb. Akad., Wien, XXXVITI, p. 488). Shell 
sub-globose, consisting of few whorls, the last of which is the largest, often carinated 
posteriorly ; aperture large, semilunar; inner lip thick with three folds, the posterior 
one of which is the strongest. Operculum broadly oval, calcareous, with a tooth 
on the inner edge, and a groove corresponding to the strong posterior fold of the 
inner lip.t+ 
The strong posterior fold of Detanira is similar to that of Clithon, but the 
want of any finer denticulation distinguishes it readily from the Neriting. The 
genus was proposed for two species, Dei. bicarinata and Hérnesi, from the creta- 
ceous fresh and brackish-water deposits of the North-Eastern Alps; the former was 
first described by Zekeli as a Rotella. In my revision of the Gosau-Gastropoda, 
p. 50 (Sitzb. Akad., Wien, 1865, Vol. LIT) I have added the Deianira Goldfussi, 
* Our nummulitic species show the same different state of preservation. 
+ The position of the operculum in the aperture is very likely quite similar to that of the Neritine, 
not that the tooth, as I supposed (I. cit.), would correspond to the posterior edge of the aperture. 
