HIND : THE MILLSTONE GRIT FAUNA 
33 
SPATHELLA LATA Sp. nOV. 
[Plate VI., Figs. 32, 33]. 
Specific Characters. — Shell broadly ovate, inequilateral, mod- 
erately gibbose, with a compressed but narrowed dorsal slope. The 
anterior end is fairly prolonged, its margin rounded. The inferior 
border is gently convex ; the posterior narrower than the anterior is 
apparently rounded, truncate in its upper portion. The superior 
border is arched in front, almost straight posterior to the umbo. 
The umbo is well marked, incurved, raised above the hinp;e and 
situated only a short distance in front of the centre of the upper border. 
Passing obliquely downwards and backwards from the point of the 
umbo is a strong ridge which soon becomes lost in the general convexity 
of the valve, which separates the rather narrow dorsal slope from the 
remainder of the valve. The escutcheon is long and narrow. 
Interior. — The anterior adductor muscle scar is rounded, not 
deep or marked off posteriorly by a ridge. The posterior oval, placed 
high up in the hollow of the dorsal slope. Mantle line entire. 
Hinge plate thickened, concave from above downwards and 
apparently edentulous. 
Exterior. — Apparently almost smooth. 
Dimensions. — Fig. 32, PL VI., the cast of a left valve measures : — 
Anteroposteriorly, 58 mm. (estimated). 
Dorsoventrally, 30 mm. 
Gibbosity of Valve, 10 mm. 
Locality. — Millstone Grit, Hazel Hill near Ripon. 
Observations. — This is a largish shell, but almost featureless, 
both in external characters and the simplicity of the hinge-plate. Some 
half-dozen specimens have been obtained from the Hazel Hill locality, 
but it has not been found elsewhere in the Marine Band. 
c 
