GASTEROPODA. 89 
PaTELLA RUGOSA, Sow. Plate XII, figs. 1, la—g. 
PaTELLaRIA sIMA, Lhwyd. 1760. Lith. Brit. Ich., t. 8, No. 436.1 
Tue Parsrure, Park. 1811. Org. Rem., vol. iii, p. 50, t. 5, fig. 21. 
PaTELLA RuGOSA, Sow. 1816. Min. Con., t. 139, fig. 6. 
— — Fleming. 1827. Brit. Anim., p. 288. 
—_ — Brown. 1849. Tllust. Foss. Conch., p. 104, t. xlviti, fig. 18. 
_ _ Morris. 1843. Cat. Brit. Foss., p. 155. 
— ANCYLOIDES, Sow. 1824. Min. Con., t. 484, fig. 2. 
— — Brown. Ilust. Foss. Conch., p. 105, t. xlviui, figs. 27—29. 
? — ~ Tessonri, Deslongchamps. Mém. Soc. Linn. de Normandie, vol. vii, t. 7, fig. 3. 
Hetcion rugosa, D’Orb. Prod. Paleéont., p. 303. 
P. Testé ovata, postice convead, anticé subconcavd, apice depresso, versis marginem 
anticum inflexo ; costulis radiantibus crebris, interstitiis lineatis ; striis alteris transversis 
decussantibus, antice congestis, testamque corrugantibus, postice remotis. 
Shell ovate, posterior side convex, anterior rather concave ; apex depressed, inclined 
towards the anterior margin ; the longitudinal radiating ribs are closely arranged, with fine 
lines between them, and decussated by encircling striae, which, upon the anterior side, are 
corrugated or compressed closely together ; posteriorly they are remote. 
The aspect of this shell varies considerably, even in specimens obtained from the same 
quarry; and these differences are irrespective of those produced by the various stages of 
growth. Some approach to the circular form, and in such the apex is more central, 
elevated, and less curved forwards; others, which are a longer oval, have the summit more 
beak-like and depressed. ‘The different degrees of magnitude in the radiating costae, and 
the depth to which they are impressed by the encircling strie, likewise contribute to the 
varieties of aspect. ‘The greater number of specimens obtained from the quarries at 
Minchinhampton Common have a rugose aspect, but those from the quarries situated to 
the north of the vale of Brimscombe are usually different; the shell becomes very thin, 
the form is more depressed, and the surface is nearly smooth, the ribs being faintly marked, 
and the encircling strize scarcely discernible. When very young, and not exceeding 6 
lines in length, the figure is more depressed, of a longer oval, nearly smooth, and the apex 
is turned, and even slightly twisted to the right side, constituting the Patella ancyloides of 
the ‘Mineral Conchology.’ It is rare to obtain the shell so small; and the Ancliff 
specimen, upon which the species was founded, is, in common with all the Great Oolite 
shells of that locality, extremely small, but the number of intermediate sizes obtained, leave 
no doubt of its identity. It occurs, indifferently, in all the shelly beds. Our largest 
specimen has a length of 25 inches, a width of 24 inches, and a height of 13 lines. 
Locality. Minchinhampton Common; Bussage ; Ancliff. 
Found also in the Stonesfield slate (Sowerdy) ; in the roestone of the Inferior Oolite at 
6 
1 « Patellaria sima, fusci coloris, cancellata major. E lapicidina Stunfeldiensi,” p. 24. 
