228 CRETACEOUS GASTROPODA 
not stronger, than the ordinary thickness of the striz of growth would produce. 
On the last whorl all the keels very often disappear, and in some specimens they 
become considerably thinner even on the penultimate whorl, while in other speci- 
mens they seem to have never attained to any great strength. In large and fully 
grown specimens there appears sometimes on the last volutions an additional 
thinner keel along the posterior suture, and a similar one is also generally to be 
found near the anterior suture. 
The base of the last whorl is strongly convex, almost smooth, and on the periphery 
eenerally provided with a slight and smooth keel. The aperture is roundish-oval, 
with very thin margins, the outer lip is anteriorly somewhat produced and laterally 
deeply insinuated, in conformity with which insinuation all the striz of growth 
are bent. D’Orbigny’s 7’. simplex or subsimplez is evidently founded upon a specimen, ~ 
on which the spiral ridges had either not been strongly developed, or had been 
worn of, their markings being, however, clearly traceable. 
Locality.—Moraviatoor, Coonum and Veraghoor, in Trichinopoly district, in 
calcareous sandstones; near Streepermatoor, about 24 miles W. by S. of Madras, 
in light coloured sandstones. 
Formation.—Ootatoor and Trichinopoly groups, to one of which probably also 
the beds of the last named locality belong. 
XXIII. Family,—SCALID. 
Scarrpm, H. and A. Adams, Gen. I, p. 220; Scazarrap#, Gray, Guide, 1857, 
p. 52; Scazarm., Chenu, Man. p. 217. 
The animals in this family very much resemble those of the Vurrirezzipa, 
with the exception, that the proboscis is usually much stronger and fleshy ; the 
mantle is enclosed and has often a rudimentary fold in front; a longitudinal groove 
on the hinder part of the foot is usually considered to be characteristic of the genus 
Scala; the front part of the foot is more expanded, than in the animals belonging 
to the last family. The greatest difference between the two is, however, exhibited 
in the dentition, the teeth of the Scazrp being all uniform, hook-like, placed in 
many series, the outer being at the same time somewhat larger. 
H. and A. Adams state, that the animals are predaceous, and this has pro- 
bably induced them to place the family in the neighbourhood of the Casszpipa. 
Certainly the predaceous habits of the animals are not very consistent with the 
phytophagous life of the families, among which they are here placed, but in such 
cases it is perhaps advisable to lay more weight upon the general character of the 
organisation and the form of both the shells and animals, than solely upon their 
mode of living. ‘Troschel classes the Scazzp# in the order PrEnoctossa. 
The operculum is horny and pauci-spiral. 
The shell is spiral, turreted ; the whorls convex, usually with numerous transverse 
ribs; the aperture round, with the margins entire, somewhat thickened and ante- 
riorly often more or less obsoletely effuse. 
