60 MOLLUSCA FROM THE GREAT OOLITE. 



Pileolus plicatus, Sow. Plate IX, figs. 36, 36a, b,c. 



Pileolus plicatus, G. B. Sow. 1823. Genera of Shells, No. 19, figs. 1 — 4. 



— — Sow. Min. Con., t. 432, figs. 1—4. 



— — Bronn. Leth. Geogn., p. 392, t. 27, fig. 6. 



— — Brown. Illust. Foss. Conch., p. 92. 



— — D'Orb. 1850. Prod. Paleont., p. 299. 



— — Bronn. Index Palseont., p. 973. 

 Patella costatula, Gold/uss. Petref., t. 177, fig. 9. 



P. Testa turbinatd; ambitu orbiculari; vertice elato, subacute, erecto; costis radiantibus 

 majoribus (16) acutis, minoribus intermediis ; costis posterioribus maximis ; margine 

 dentatd; basi in medio convewiusculd, ad perip/ieriam subconvexd; peripherid integrd 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. lavis ; the usual basal diameter being about 

 3 lines, and very rarely exceeding 4 lines. Pileolus plicatus is scattered, indifferently, 

 over the shelly beds, but in fewer numbers than the other species; the shell being 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. 



Pileolus l^ivis, G. B. Sow. Plate IX, figs. 37, 37a, b. 



Pileolus LiEvis, G. B. Sow. 1823. Genera of Shells, No. 19, figs. 5 — 8. 



— — Soiv. Min. Con., t. 432, figs. 6—8. 



— — Brown. Illust. Foss. Conch., p. 92, t. 44, figs. 16, 17. 



— — DOrb. 1850. Prod. Paleont., p. 299. 



— — Bronn. 1848. Index Palseont., p. 973. 

 ? Patella mamillaris, Gold/uss. Petref., t. 177, fig. 10. 



? — papyracea, Bronn. Lethsea Geogn., pi. 27, figs. 7, a, b. 



P. Testa parvd, conico-depressd, Icevi, aut sulcis raris, obsoletis notatdj basi in medio 

 convewiusculd. 



Shell small, conical, but much depressed ; sometimes discoidal, smooth, or with a few 

 faintly-marked longitudinal irregular sulcations ; base rather convex in the middle part. 



