127 
DESCRIPTION OF SPECIES FIGURED. 
x 
Tricuires unpuLatus, Lycerr. Pl. I, fig. I.; Pl. II, figs. 1, 2. 
The genus Trichites is fully described by Dr. Lycerrrt, Vol. I, 
p- 42, and by Morris and Lyczrr in the Monograph of the 
Mollusca of the Great Oolite. TT. wndulatus is described in 
Vol. I, p. 46, as follows:—“Shell oblong, umbones ribs obscure, 
few, concentric, irregular, and undulated, sometimes obsolete 
in the larger valve. The smaller valve unknown.” No figure 
is given. 
It will be observed from the figures that there is great 
variability in the form of this shell. The figure on Plate I is 
much more convex and narrow than that on Plate II. It has 
also regular lines of growth, of which the latter is nearly 
destitute. Each shell is about 10 inches long, one is 8 inches 
wide, the other 6 inches. 
Tricuttes Noposus. Mor. and Lyc. PI. III. 
The figure in the Monograph of the Great Oolite is that of 
the left valve. The figure now given is the interior of the 
right valve. It is nearly flat. There is a long ligamental 
groove down the straight side of the shell. In other respects 
the shell is fully described in the Monograph. 
PwHastANELLA Costata. PI. IV, fig. 1. 
Shell conical, spire elevated, acute, whorls six, their height 
equal to the half of their opposite diameters, convex, trans- 
versely costated, cost regular, raised, longitudinally striated, 
the last whorl much inflated, aperture ovate, its height equal 
to half the length of the entire shell. The coste on the 
anterior part of the last volution are wider apart than on the 
other portions of the shell, and in the interstitial spaces fine 
lines may be detected. The longitudinal striz are only visible 
with the aid of a magnifier. Height, 1 inch. 
Geological position and locality,—the Clypeus Grit of 
Rodborough Hill. Rare. 
tA : Ng h 
=. ¥v unthr Aga urd aha q KA eet ; Ved. I. 
at ) \Ub wen inn hartadtr 
etal 
