GASTEROPODA. 83 
Trocnotoma TaBuLata. Plate X, figs. 17, 17a. 
T. Testa conicd, apice acuto, anfractibus (5) tenuissimé striatis subquadratis, medio 
angulatis ; anfractu ultimo subangulato ; basi planato, profunde excavatd. 
Shell conical, apex acute; whorls 5, very finely striated, step-like, and angulated in 
their middle portion ; the last whorl is angulated, the base flattened and deeply excavated. 
The sides of the volutions are nearly flat, both above and beneath the angle, which, 
together with the smallness of the encircling rib, fineness of the strie, and acute apex, 
serves to distinguish it from 7. calizv or 7. afinis, Desl., which is an Inferior Oolite species. 
It is moderately common. Height 10 lines, basal diameter 12 lines. 
Our figure is of medium dimensions. 
Locality. Great Oolite of Minchinhampton. 
Trocnotoma oprusa. Plate X, fig. 15a, d. 
T. Testa turbinatd; apice obtuso; anfractibus (5) convexiusculis, striatis, basi dilatatd, 
medio laté excavatd; peripherid striata. 
Shell turbinated; apex obtuse ; whorls (5) rather convex, striated, the lower surface 
dilated, its middle widely excavated, periphery striated. 
The encircling rib is large but depressed, and contributes to give a convex aspect to 
the whorls; the striz are large, the general figure being more turbinated, or less regularly 
conical than is usual with the Zrochotome, each advance of growth was equal to two thirds 
of a volution: it is by far the most abundant of the genus. Height 10 lines, basal 
diameter 13 lines. 
Locality. Great Oolite of Minchinhampton. 
TROCHOTOMA EXTENSA. Plate X, figs. 19a, 193. 
T. Testd conicd; apice obtuso, depressd; anfractibus (A, 5) subangulatis, planis, et 
levibus; basi ampla, profunde excavatd. 
Shell conical; apex obtuse, depressed; whorls (4, 5) subangular, flattened, and 
smooth ; base wide, rather convex; cavity large and deep. 
This is by far the largest and most rare of the Great Oolite species, the base is 
enormously wide, and the cavity very large. Height 16 lines, basal diameter 30 lines. 
Locality. Minchinhampton. 
