132 CRETACEOUS GASTROPODA 
smooth with broad sulei; externally inflated forming a varix, but not much thick 
ened; canal usually somewhat produced; columella solid. This genus ought to be 
certainly distinguished from Tritoniwm and the other genera, being well charac- 
terized by the thinness of the shell as compared with other Zzrrowup#. We noticed 
the same difference, accompanied with other distinctive characters (as stated), on 
two species from the South Indian cretaceous rocks, the description of which will 
be found more in detail farther on under this generic heading. Chenu entertains, as 
T believe justly, some doubts as to the species attributed by Adams to this genus. 
If the rit. Tranquebaricum, Linn., be not separated from Simplum, there is 
certainly no reason to do so with Tr. clandestinwum, Lamk. for both have the 
characteristic form and thickened outer lip of Stmplum, except that the varices 
become on the upper volutions more or less obsolete. There is usually only one 
varix on the last, and sometimes one, two, or three preceding ones well developed on 
the previous volutions, but I do not think that there is any great necessity for 
separating these forms from Simplum, save on account of the few differences in the 
structure of the shell; certainly they are not to be united with Zit. cancellatum, 
Lamk., Z. Oregonense, Say, LZ. Chemnitzii, Gray, and others in one genus. The 
Trit. (Buccinum) glaciale, Miller, ought, I believe, to be placed here and not under 
Bucemun. 
10.—Argobuccinum (vide Adams’ Gen. I, p. 104). This genus would seem to 
differ only by the more solid structure of the shell, and by the outer lip being 
internally thickened and_ dentate, the canal short, recurved; it could be retained 
for Tr. scabrum, King, Ranella Argus, Lamk., R. vexillum, Sow., and a few tertiary 
fossil species. The Zit. rude, Brod., appears rather to be a Pollia. 
11.—Hindsia,* Adams, 1850; (Nassaria in Adams’ Gen. I, p, 123 ; Hindsia 
of Chenu). Excepting the last varix on the margin of the outer lip, there is 
no other one distinguished from its size, although the whorls are transversally 
numerously ribbed; the canalis produced and recurved; the aperture roundish ; 
the inner lip transversally grooved, and the outer lip internally thickened and 
dentate. These characters distinguish the shells of this genus easily from Lagena 
and Argobuccinum. 
Gray (Guide, 1857, p. 48) does not seem to be inclined to separate these forms 
from Tritoniwm (Triton) at all; and Adams, Chenu, and others placed the genus 
under the Buocrvip#, next to Phos, Montf. H. and A. Adams refer (loc. cit. p. 127) 
to some distinctions in the animals between Nassaria and Tritonum, but certainly on 
comparing these with the animals of most of the Buocrrps#, it may be seen that 
the dilated foot, the placing of the eyes, and the straight siphon are far more like in 
the Trrronupm than is generally the case in species of the Buccryrp#. The 
shell from its consistency and ornamentation is decidedly that of a Tritoniwm and 
* Morch (Proceed. Zool. Soc. Lond., 1862, p, 227) says ‘the first species is Nassa lyrata, Gmel., p. 3794; Mart. IV, 
Figs. 1122-1123. If the quotation of Gmelin is right, the type is Mangelia; but if Martinis’ figures are correct, the 
type is Buce. nivewm, Gmel, The latter, however, is not probable; and therefore the name WVassaria must not be 
used for Hindsia, H. and A. Adams.’ 
