176 CRETACEOUS GASTROPODA 
T am not aware whether the forms, which I have quoted as Itierta, possess a 
sutural band like Nerinea proper; none of the figures show it distinctly. Iam 
quite at a loss for the present where to place the two jurassic species, Werinea 
Mandelslohi, Bronn, and N. gradata, D’Orb. If they do not, however, possess a sutu- 
ral band, I do not think that they can be rightly excluded from the genus Itieria. 
Matheron instituted his genus, as I have already mentioned, only for the one species, 
Ner. Cabanetiana; but if we compare with this, for instance, the Ner. pupoides, 
it becomes evident that there is apparently no other important distinction between 
those two, than that the latter has one additional plait on the inner lip. We know, 
however, from species like Itieria abbreviata and others that this second fold is like 
the one on the outer lip, sometimes present, and in other cases wanting. In some 
other species there seem to be three plaits present, as in typical Obeliscus; we can- 
not therefore give the existence and number of these plaits an absolute generic 
value, although they always may help us in characterizing species. 
A second character, to which M. Matheron has drawn attention, is the abbre- 
viation of the spire. This appears to me of far less importance. TI have had a good 
deal of experience in collecting large suites of Nerinee and Acteonelle, and my im- 
pression is, that both these genera were principally inhabitants of shallow beaches 
between high and low water-mark, and that they often lived on stony ground or on 
coral reefs as the recent Obeliscus usually do. Itis not often the case that a shell, 
which is to a great extent almost involute in the first stage of growth, becomes 
afterwards merely turreted, and this apparently turreted form is only produced by 
an. erosion of the posterior margins of each whorl. Much more frequently it 
happens that the spire of the large shell is more or less eroded on the stony 
ground on which it lived, or before it had been finally imbedded in the rock. In 
some specimens this occurs probably during the young state of age, in others later, 
and again in some, which live in favorable and sheltered places, perhaps never, 
or to a much smaller degree. I donot know whether I am quite correct in 
these statements, but they have been derived from actual and practical observa- 
tions. I may refer here to a few figures of Itieria abbreviata in the ‘ Jahrbuch Geol. 
Reichs-Anstalt’, Wien, Vol. XIII, page 48, which species and the few described by 
Pictet are the only cretaceous forms apparently belonging to Ltieria proper. 
Allthese observations induce us to extend Matheron’s name to forms with a coni- 
cal or even turreted spire. It is due to Pictet and Campiche, that they have again intro- 
duced the name J¢ieria into the literature of fossil Mollusca, for D’Orbigny seems to 
ignore the genus altogether when speaking of his Wer. Cabanetiana, although it was 
certainly not unknown to him when he claimed the priority of his Acteon. The 
authors of the Materiaux pour la Paléontologie Suisse, 3me. ser., add to Matheron’s 
species two other somewhat different forms, which we would be rather inclined to 
separate under the following designation of 
