278 CRETACEOUS GASTROPODA 
discovery of specimens with perfect apertures. The Rissoa Winkleri of the same 
author is a Kedlostoma. 
1. RissoA OLDHAMIANA, Stoliczka, Pl. XVI, Fig. 9; Pl. XX, Fig. 18. 
Riss. testa turrito-elongata, apice acuminata; anfractibus convexis, spiraliter 
numerose striatis, transversaliter costulatis ; costulis fere rectis, ad marginem ante- 
riorem atque prope medium evanescentibus ; columella solida, ad terminationem con- 
spicue torta; apertura ovata, parum obliqua, antice sub-effusa, postice rotundate 
angulata ; labro extus varicoso, in margine acuto. 
Spiral angle 35°; sutural angle 15°5°. 
Height of aperture : totalof shell ... (considered as 1:00) neOSGs 
Height of penultimate whorl : its width ( . 3) Ole 
Shell rather elongated and turreted, composed of numerous, strongly convex 
volutions, the last of which is shorter than the spire. Each whorl is ornamented 
with many spiral stris and with transverse ribs, which are almost straight and 
become obsolete towards the anterior margins, as well as on the middle portion of 
the last volution. The basis is considerably produced and also spirally striated. 
The aperture is oval, somewhat oblique and anteriorly obsoletely effuse; the outer lip 
with a strong, external varix, but sharp on the peristome itself; the columella 
distinctly twisted at its termination. 
Locality —Garudamungalum ; only two specimens have been found in bluish, 
calcareous sandstone. 
Formation.—Trichinopoly group ;—principal beds of Ammonites peramplus, 
Mant, 
2. Ruissoa TROPICA, Stoliczka, Pl. XX, Fig. 19. 
Riss. testa ovate elongata, spira conica, acuminata; anfractibus paulo convexis, 
spiraliter striatis, transversaliter costulatis; una vel duabus striis anticis ceteris 
fortioribus, costulis arcuatis decussantibus minute-granulosis ; ultimo anfractu sub- 
inflato ; basi producta, spiraliter striata, striis anticis fortioribus ; apertura ovate 
obliqua, antice sub-effusa; labio incrassato ; columella ad terminationem torta; labre 
extus varicoso. 
Spiral angle 50°; sutural angle 7°. 
Height of aperture : total of shell ... (considered as 1:00) roo vavede OI40, 
Height of penultimate whorl : its width ( eA sass) saanl en DE N/3 
An elongated, ovate and somewhat tumid shell, the whorls being slightly con- 
vex, the last a little ventricose. Each of the whorls is ornamented with spiral striz, 
which are crossed by very numerous, but thin and curved, transverse ribbings, 
so as to produce a fine granulation. One or two of the spiral strie near the 
anterior margin are usually somewhat thicker than the rest. The basis of the last 
