372 CRETACEOUS GASTROPODA — 
junioribus spiraliter striatis, omninis striis incrementi minutis, obliquis notatis, 
ultimo ad peripheriam rotundate angulato ; basi subconvexa, in medio impressa ; 
apertura quadrangulari obliqua ; labro ad basin margine tenwi imstructo, sinuoso ; 
labio paulo incrassato ; columella solida, antice torta atque incrassate terminanti. 
Spiral angle 65°; sutural angle 5.° 
Height of shell about equal to the diameter of the basis of the last whorl. 
Height of one whorl : its width (considered as 1-00) ... ood 0-40. 
Shell regularly conical, apex obtuse or mammillate, whorls flat, along the 
upper and lower margins often slightly thickened, in young specimens spirally 
striated, in all stages of growth, however, marked with fine oblique transverse 
strize; last whorl roundish at the periphery; basis slightly convex, and in the 
middle somewhat depressed. ‘The aperture is sub-quadrangular, very oblique, the 
outer margin being sharp, and laterally as well as at the basis deeply indented ; 
the inner lip somewhat callous and smooth; the columella twisted and anteriorly 
terminating with a thickened point. In young specimens the last whorl is sharply 
angular at the periphery and flat at the basis. 
This is a typical species of Tectus, and is closely allied to several recent forms 
from our eastern seas. It has the columellar lip very distinctly twisted anteriorly 
and thickened, thus being readily distinguished from species of Trochus (as res- 
tricted). 
Of cretaceous species I may mention Trochus Zollikoferi, Pictet and Camp.., 
(Mat. p. 1. Pal. Suisse, 8me. Ser., p. 518, pl. 86, figs. 4-5) from the -“Urgonien of 
Switzerland, being distinguished from young specimens of Tect. tumulicus merely 
by the presence of a narrow umbilicus. 
Locality —Comarapolliam and neighbourhood of Avrialoor, in whitish sand- 
stone; not rare. 
Formation.—Arrialoor group. 
2. Trctus suncEus, Stoliczka, Pl. XXIV, Fig. 3. 
Tect. testa regulariter conica, spira acuminata ; anfractibus planiusculis, suturis 
vie impressis junctis, spiraliter jugis circiter septenis subtuberculatis atque approxi- 
matis instructis, ultimo ad peripheriam carina subrugosa tnstructo; basi applanata, 
spiraliter striata ; apertura quadrangulari, columella solida et torta. 
Spiral angle 32°; sutural angle 4°. 
Approximate height of shell : diameter of its basis (consd. as 100)... 124. 
Height of one whorl : its width Re aot eed tuss svel-0.0) irene Ojai 
This species is distinguished by its attenuated shape, and the large number 
of closely arranged, spiral ridges, which are ornamented with spirally elongated 
tubercles, and often alternate with others of lesser thickness. One or two of the 
anterior ridges, which are placed nearest to the suture, are generally somewhat 
stronger than the rest. All the tubercles of the respective ridges are arranged 
in transverse rows, having the appearance of indistinct ribbings. The surface of 
the shell is not perfectly well preserved, for it does not appear improbable that 
the tubercles were much more pointed, as they are represented in our figure. 
