92 MOLLUSCA FROM THE GREAT OOLITE. 



P. Testa conicci, depressd; ambitu ovali ; apice acuto, antemediano ; costulis radi- 

 ant thus incequalibus irregularibus, jlexuosis ; striis transversis tenuissimis, irregularibus. 



Shell conical, depressed ; base oval ; apex acute, placed anterior to the middle of the 

 shell ; ribs radiating, unequal, irregular and waved ; striae transverse, irregular, and 

 very fine. 



The radiating ribs are sometimes only visible towards the margin ; the lines of growth 

 are few and uncertain ; as in the other Patella, the degree of elevation varies considerably, 

 the apex approaching more nearly to the anterior border in such as are depressed ; the 

 colours are sometimes partially preserved. 



Locality. It is not uncommon, and occurs in all the shelly beds of the Great Oolite 

 near Minchinhampton. Our largest specimen is 1^ inches in its longer diameter. 



M. D'Archiac describes this species as occurring in the Great Oolite of Aubenton, 

 France, where it is rare. 



Patella suprajurensjs, Buv. Plate XII, figs. 9, 9a. 



1 Patella, suprajurensis, Buvignier. 1843. Mem. Soc. Philom. de Verdun (Meuse), 



pi. 5, fig. 10. 



P. Testa ovato-depressd ; apice subcentrali ; ambitu ovali; striis incrementi irregu- 

 laribus, distinctis ; striis concentricis tenuissimis crebris. 



Shell ovate, depressed ; apex subcentral ; base oval ; lines of growth irregular, strongly 

 marked ; concentric striae closely arranged and very fine. 



The absence of radiating costae sufficiently separates this from P. Aubentonensis, the 

 general figure of which it nearly resembles ; the lines of growth are likewise much more 

 strongly marked. 



Locality. It is comparatively rare, and is not confined to any of the shelly beds of the 

 Oolite at Minchinhampton. Found also in the Portland limestone of Varennes. {Buv). 



Patella arachnoidea. Plate XII, figs. 8, 8a, b. 



P. Testa parvd, ellipticd et conicd; apice acuto centrali; costulis longitudinalibus minutis 

 et distantibus; lineis transversis numerosis, elatis et irregularibus. 



Shell small, elliptical and conical ; apex acute, central ; with longitudinal, minute, and 

 distant ribs ; transverse lines very numerous, elevated, and irregular. 



This small species has an elevated, acute apex, and displays under the magnifier a 

 beautiful net-work kind of surface ; the encircling lines are three or four times more dense 

 than the longitudinal elevations. The form is nearly that of Pileolus plicatus, but more 

 acute, and the character of the surface is altogether different. 



Locality. The shelly beds at Quarhouse, which correspond to the planking of Min- 

 chinhampton Common, have furnished our specimens. 



