174: CRETACEOUS GASTROPODA 
5. Turbonilla,* Leach, 1826 (? 1819) (H. and A. Adams’ Gen. I, 230).—It is 
known that, when Risso first introduced the name Zurbonilla of Leach, he described 
under it species with and without a columellar fold. Several conchologists, and 
among them Deshayes in his last edition of the Paris fossils, retain the genus in the 
same sense as Risso, others have proposed distinctions in various ways. ‘The name 
Turbonilla was consequently applied to species with a fold, while others without the 
same have been referred to Chemnitzia of D’Orbigny. Again, the names Turbonilla 
and Chemnitzia were considered as identical by Gray, Deshayes and others and this 
once admit ted, another time the other name is allowed to have priority. In many 
works on recent conchology the name Turbonilia was reserved for the non-plicated ° 
species only, and the confusion would be probably cleared up in the easiest way, if 
the genus was retained in the sense as introduced by H. and A. Adams in their 
Genera. Ohemmitzia as subsequently commented on by D’Orbigny (in his Pal. frane. 
terr. jur.) must be kept thoroughly distinct. The name was founded first upon a pli- 
eated Lurbonilla, for which A. Adams proposes now the name Hlusa; there is there- 
fore, strictly speaking, no reason whatever to regard Turbonilla and Chemnitzia as 
identical. We shall speak subsequently of the latter genus in the family Lozmupz. 
6. Eulimella, Forbes, 1846 (H. and A. Adams, Gen. I, p. 233).—According to 
the account given of the animal, this genus, like Zwrboniila itself, cannot be excluded 
from the family Pyrramwzprriips. The whorls have in fact the typical squarish 
shape, with flattened, not produced basis, as is invariably the case in Chemmnitzia. 
Ga. (Aciculina),+ Deshayes, 1864 (Paris foss., 2nd edit., Vol. IT, p. 530). By 
this name have been called a few eocene species which differ from Hulimella by a 
greater convexity and perhaps a larger number of whorls. The (Aciculina) 
emarginata, Desh. (loe. cit. p. 5383, Pl. XXV, Figs. 25—27, not 26—28) is a Chittia, 
and the other species may be regarded as transitional forms to those smooth species 
of the Czrrrazopsipm, which H. and A. Adams called Alaba. 
Of all these generic forms noted under numbers 83—6 not a single species has 
yet been fully ascertained to occur in eretaceous strata, although a large number of 
species are known from the eocene and neogene beds. It is, however, very probable 
that when more attention has been paid to those little shells, they will not be found 
wanting in the mezozoic formations. The only cretaceous species of Odostomia 
will be described subsequently from our South Indian cretaceous deposits. The ere- 
taceous Zurbonille, described by Conrad (Journ. Acad. Nat. Sc. Phil. iv) are referred 
by Gabb in his ‘Synopsis of eretaceous fossils’ to Chemnitzia, which appears in 
general correct, but a few species like Zwrb. Spillmani are undoubtedly more allied 
to Turbonilla than to Chemnitzia. 
* Dunkeria, Carpenter, 1858 (H. and A. Adams’ Gen. II, p. 622) has been proposed as a sub-genus for cer- 
tain forms of Turbonilla with tumid and cancellated whorls, but it is considered by A. Adams as more allied to 
Aclis and we shall notice it, therefore, in the Evzzmrpx. The species are mostly from Mazatlan. 
+ This name has been already, in 1853, used by H. and A. Adams (vide Gen. I, p, 121) as a sub-genus of 
Nassa. 
