GASTEROPODA. 89 



Patella rugosa, Sow. Plate XII, figs. 1, \a — g. 



Patellaria sima, Lhwyd. 1760. Lith. Brit. Ich., t. 8, No. 436. 1 

 The Patellite, 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. Illust. Foss. Conch., p. 104, t. xlviii, fig. 18. 



— — Morris. 1843. Cat. Brit. Foss., p. 155. 



— ancyloides, Sow. 1824. Min. Con., t. 484, fig. 2. 



— — Brown. Illust. Foss. Conch., p. 105, t. xlviii, figs. 27 — 29. 



? — Tessonii, Deslongchamps. Mem. Soc. Linn, de Normandie, vol. vii, t. 7, fig. 3. 

 Helcion rdgosa, D'Orb. Prod. Paleont., p. 303. 



P. Testa ovatd, postice convexd, antice subconcavd, apice depresso, versus marginem 

 anticum injlexo ; costulis radiantibm crebris, interstitiis lineatis ; striis alteris tramversis 

 decussantibits, 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 striae, 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 striae scarcely discernible. When very young, and not exceeding 

 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 2^ inches, a width of 2£ inches, and a height of 13 lines. 



Locality. Minchinhampton Common ; Bussage ; Ancliff. 



Found also in the Stonesfield slate {Sowerby) ; in the roestone of the Inferior Oolite at 



1 " Patellaria sima, fusci coloris, cancellata major. E lapicidina Stunfeldiensi," p. 24. 



