322 , CRETACEOUS GASTROPODA 
species, formerly described by different authors from the American cretaceous rocks, Gabb retains 
under Heleion only H. tentorium, Mort., and quotes besides three, partly doubtful species of Zectura, 
as 7. occidentalis, papillata and parva of Meek and Hayden (see Am. Phil. Soc., VIII, pp. 118 
and 138). Lately (Paleont. Calif., 1864, I, p. 141) two new species have been added by the 
same author, Hl. circularis and dichotoma. Guéranger, in his Album Pal. de la Sarthe, 1867, 
(pl. 14, figs. 21 and 34) gives a figure of Hele. Orbignyi and of a doubtful H. truncatum, 
but not of any of the other three species which he names in his Repertoire Paléont., 1853, p. 33. 
An undetermined species of Zectwra is mentioned in the ‘ Paléontologie’ of Tchihatcheff’s ‘ Asie 
Mineure,’ ete., (1866, p. 90, pl. 2, fig. 7,) under the name of demea. Tichwald (Leth. Ross., XI, 
lior., 1867, pp. 805-806) describes from the cretaceous rocks of Russia four species of Hedcion, 
H. sulciferum, planissimum, subtile and clavatum; except the last none of the species can be 
considered as sufficiently certain with regard to generic determination. 
The South Indian cretaceous rocks have yielded us four species, two of which have been 
already described by Prof. Forbes under the names of Calyptrea elevata and corrugata. The 
former was by D’Orbigny referred to He/cion, though it seems more likely to be a Tectura ; 
the latter is to all appearance a good species of Helcion. In each of these genera there is an 
additional new species described as Zectura Footeana and Helcion carnaticum. On the whole, compared 
with other families, the 7zeTURIDZ appear to be very rare shells in our cretaceous deposits, for we 
have seen only single specimens of all these species. 
LXXIV. TECTURA, Audouin and YW. Edwards, 1839. 
1. TectuRA (?) ELEVATA, Forbes, sp., Pl. XXVIII, Fig. 6. 
1846. Calyptrea ? elevata, Forbes, Trans. Geol. Soc., Lond., VII, p. 187, Pl. XII, Fig. 10. 
Tect. testa late conica, in superficie sublevigata, striis incrementi concentricis, 
subrugosis notuta ; apice obtusiusculo, fere central. 
We have seen in the collection of the Geological Society of London only 
Prof. Forbes’ original specimen of this species from which our figure is taken. 
The surface of the shell, so far as preserved, is smooth, but there are distinct traces 
of somewhat irregular, concentric ribbings present. The shell itself is rather 
thick, as compared with that of Calyptra and Anisomyon. On the apex, which is 
very nearly central, the shell is almost entirely removed, but I have not been able 
to observe any trace of an internal process at this place; I therefore suspect 
that the species correctly belongs to Zectura and not to Calyptra; the surface 
is very much worn off. There seems to be a very shallow depression below the 
apex, which appears to have been very slightly bent to one side. 
It is difficult to understand on what grounds d’Orbigny declared the Calypt. ? 
elevata of Forbes, which he quotes as a Patella! (Prod. II, p. 232), to be identical 
with the Acmea Reussii, Geinitz. Neither the height of the shell, nor the form 
of the aperture, or of the apex are in any way identical in the two species; 
moreover, the last named one appears to be a true Axisomyon of the family 
Lnperipaé. 
Locality.——Pondicherry, in light coloured bluish sandstone. 
Pormation.—Arrialoor group. 
