60 MOLLUSCA FROM THE GREAT OOLITE. 
PiLEous piicatus, Sow. Plate IX, figs.36, 36a, 4, c. 
Prineo.wvs piicatus, G. B. Sow. 1823. Genera of Shells, No. 19, figs. 1—4. 
== — Sow. Main. Con., t. 432, figs. 1—4. 
— — Bronn. Leth, Geogn., p. 392, t. 27, fig. 6. 
— _— Brown. Mllust. Foss. Conch., p. 92. 
_— — D Orb. 1850. Prod. Paléont., p. 299. 
_— _ Bronn. Index Palzeont., p. 973. 
PATELLA CosTaTULA, Goldfuss. Petref., t. 177, fig. 9. 
P. Testa turbinatd; ambitu orbiculari ; verticé elato, subacuto, erecto; costis radiantibus 
majoribus (16) acutis, minoribus intermediis ; costis posterioribus maaimis ; margine 
dentatd; bast in medio convewiusculd, ad peripheriam subconvead; peripherid integra aut 
subsinuatd. 
Shell turbinated, suborbicular, summit elevated, erect, and rather acute; ribs radiating, 
the larger series (16 in number) are acute, with smaller ones between them; the posterior 
ribs are the largest and most distant; the margin is toothed, the base is convex in its 
middle part, and slightly convex at the periphery; the periphery is entire, and slightly 
sinuated. 
Four of the posterior ribs occupy one third of the circumference; they are more elevated 
and distant than the others. The specimens of this species in the Great Oolite never 
occur of so large a size as those of P. Jevis; the usual basal diameter being about 
3 lines, and very rarely exceeding 4 lines. P2/eolus plicatus is scattered, indifferently, 
over the shelly beds, but in fewer numbers than the other species; the shell bemg very 
thick and strong, is usually entire and uncompressed; both species are always found in 
the upright position. 
Locality. Minchinhampton Common; Ancliff, Wiltshire; Langrune, France. 
Pitzoius Lavis, G. B. Sow. Plate IX, figs. 37, 37a, 6. 
PILEOLUs Lazvis, G. B. Sow. 1823. Genera of Shells, No. 19, figs. 5—8. 
— — Sow. Min. Con., t. 432, figs. 6—8. 
— — Brown. IIllust. Foss. Conch., p. 92, t. 44, figs. 16, 17. 
_— — DOrb. 1850. Prod. Paléont., p. 299. 
— —  Bronn. 1848. Index Paleont., p. 973. 
? PATELLA MAMILLARIS, Goldfuss. Petref., t. 177, fig. 10. 
?— ~papyracra, Bronn. Lethzea Geogn., pl. 27, figs. 7, a, 6. 
P. Testa parva, conico-depressd, levi, aut sulcis raris, obsoletis notatd; basi in medio 
conveatiusculd. 
Shell small, conical, but much depressed ; sometimes discoidal, smooth, or with a few 
faintly-marked longitudinal regular sulcations ; base rather convex in the middle part. 
