32 
HIND : THE MILLSTONE GRIT FAUNA 
Interior. — The anterior adductor muscle scar is large and occupies 
the greater portion of the anterior part of the valve. Hinge-plate 
apparently edentulous. 
Exterior. — The shell is ornamented by somewhat irregular 
lines and striae of growth. 
Dimensions. — Fig. 24, PI. V., measures : — 
Anteroposteriorly, 26 mm. 
Dorsoventrally, 14 mm. 
From side to side, 10 mm. 
Locality. — Millstone Grit, Hazel Hill. 
Observations. — Two specimens of this species have occurred, 
both are bi-valved and casts of the interior. The general shape and 
the narrow elongate anterior end at once distinguish the shell from 
T. cuneiformis. 
allorisma tumida, sp. nov. 
[Plate VI., Figs. 26, 27]. 
Specific Characters. — Shell tumid, inequilateral, transverse. 
The anterior end blunt and rounded is very short. The superior 
and inferior borders sub-parallel, the posterior border bluntly sub- 
truncate. The umbones are blunt, incurved, not much raised and 
transverse. The dorsal slope is comparatively small, but compressed, 
lunule and escutcheon well developed. 
Interior. — Anterior adductor scar large. Hinge-plate not seen. 
Exterior. — The surface of the shell, especially in the anterior 
portion, is ornamented with a few broad concentric folds and sulci 
which become obsolete on the posterior part of the valve, the dorsal 
slope is smooth. 
Dimensions. — PI. VI., Fig. 26, a small example measures : — 
Anteroposteriorly, 19 mm. 
Dorsoventrally, 16 mm. 
From side to side, 11 mm. 
Locality. — Millstone Grit of Hazel Hill. 
Observations. — Four examples of this species have been found 
but the material is poor and leaves much to be desired. It is not 
likely to be mistaken for any other species of the genus. 
