Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/251

Rh J. S. GARDNER ON BRITISH CRETACEOUS PATELLID^ ETC. 203

Chama in aspect ; its mimicry of the jN"eocomian Exogyrce is almost as remarkable as that of the common Gault Inoceramus by Calyptrcea concentrica. A unique specimen, from Donnington, is preserved in the Cambridge Museum. Crejiidulce first appear in Cretaceous rocks.

Crtjcibulum gigantetjm, sp. nov. Lower Greensand. PI. IX. figs. 1, 2 ; PI. VII. figs. 3, 4.

Orbicular, patelliform, depressed, height equal to 4- the length ; apex obtuse, central or subcentral ; posterior region slightly hol- lowed out, anterior very slightly concave ; surface irregularly marked with lines or folds of growth, without ribs. The scar is deeply impressed, and extends sinuously from near the margin, about half- way to the apex, forming a sharp bend, something like a Greek epsilon.

The larger specimen shows only a slight depression along the scar-line, but appears to be specifically the same as the one from Shanklin, although it has the apex less central. The larger speci- men is from Hythe, and in my collection ; the smaller, from Shanklin, is in the Jermyn-street Museum.

The genus is here, for the first time, recorded as Cretaceous.

CAPULITLE.

Pileopsis neocomiensis, sp. nov. Lower Greensand. PI. VII. figs. 1, 2.

Orbicular, depressed ; rather compressed laterally, giving the aperture a slightly pentagonal aspect ; apex small, acute, recurved, not spiral, about -J posterior ; surface irregularly marked with con- centric lines of growth, with a texture similar to that of Ostrea.

The shell is from the Tealby limestone of Donnington, and is in the Woodwardian Museum ; the surface is pitted by the pisolitic iron- stained grains which largely compose the matrix of the stone in which it was found. It is an undoubted Pileopsis, and strongly re- sembles the British P. ungarica.

PiLEOPsts dubia, sp. nov. Gault. PI. VII. fig. 24.

Shell thin, orbicular, scutiform, very depressed, with minute flexuous striae ; apex subcentral, spiral (?). The muscular impres- sion can be traced ; and there is no sign of septum.

The specimen upon which the present species is founded is unique. It was obtained at Folkestone, and is in my collection. It resembles Patelloidea, which has not hitherto been noticed fossil.

Pileopsis Seeleyana, sp. nov. Upper Greensand. PI. VII. fio-s, 5-7.

Shell rather thick and suborbicular, scutiform, depressed ; apex subcentral, slightly anterior ; margin entire, laminated ; shell very finely and evenly striated, the striae being only visible by aid of a strong lens.