BIVALVIA. 43 
is sinuated; the anterior side has a large, rounded, but compressed lobe; the posterior 
border is very convex, and is curved elliptically; the surfaces of the valves have a few 
large, irregular and distant plications. 
The length is twice the breadth, and two fifths greater than the convexity of the united 
valves. 
The very inflated figure, the curvature of the valves, and the distinct anterior broad 
sulcation, distinguishes it from other Jurassic species ; some specimens, smaller and appa- 
rently younger, cannot perhaps be distinguished from Modiola reniformis, Sow., for the 
species varies in the length, curvature, and convexity. 
Geological Positions and Localities. his species is figured upon the authority of 
specimens in the Museum of Practical Geology, which are stated to have been collected in 
the Cornbrash of Melbury Osmond. It is common in the Inferior Oolite of the southern 
counties. 
CucuLL#a corauuina. Tab. XXXIX, fig. 3. 
CucuLLmA oBLONGA, Phil. Geol. York., i, t. 3, fig. 34, non Sow. 
— coraLLtina, Damon. Geol. Weymouth, Suppl., pl. 4, fig. 8. 
Testa inflata, subrhomboidali, subequilaterali, umbonibus magnis medianis acutis, 
incurvis, latere postico abbreviato abrupte truncato, area cardinis brevi, superficie lineis 
longitudinalibus crebris, irregularibus aliis radiantibus subobsoletis decussata. 
Shell much inflated, subrhomboidal, nearly equilateral; umbones large, mesial, 
incurved, elevated, slightly oblique, and nearly in contact. 
The anterior side is produced and rounded, the posterior side is very short, abruptly 
truncated, slightly excavated, and separated from the other portion of the surface by a 
strongly defined subacute angle ; the hinge area is short and not wide; the surface has 
densely arranged, irregular, longitudinal lines, decussated by others radiating, but much 
less clearly defined. 
Dimensions.— Height, three fourths of the length. 
A very short, tumid, abruptly truncated Cucullza, possessing these characters in a greater 
degree, and less oblique than any of the shorter examples of C. oblonga, Sow.; the latter 
shell has also several large, widely separated, radiating lines upon the anterior side, of which 
our species is destitute. It appears to be identical with Cucullea oblonga, Phil., from the Coral 
Rag, at least with the more short examples of that species, for the Coral Rag shell presents 
great variability in its general figure, more especially in that of the posterior side, and it is 
easy to obtain specimens which insensibly connect the shorter with the more lengthened 
and oblique forms; it rarely happens that the surface ornamentation can be discovered, 
but the portions of the surface obtained agree with that of the Cornbrash shell. 
Geological Positions and Localities. Cucullea corallina occurs rarely in the Cornbrash 
of the Yorkshire coast, but is abundant in the Coral Rag of Pickering and of 
Oxfordshire. 
