42 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



Geological Position and Localities. It occurs rarely in the Cornbrash of Scarborough. 

 Dr. Oppel records it in the same geological position at Marquise, near Boulogne ; also at 

 Egg, near Aarau, Switzerland. Goldfuss records it at the latter locality, and at Basel. 



LIMA RIGIDULA, Phil., sp. Tab. XXXIII, figs. 7, 7 a. 



PLAGIOSTOMA RIGIDULUM, Phil. Geol. York., i. t. 7, fig. 13. 



Testa elongata, convexa, per-obliqua, umbonibus obliquis, acutis, auriculis parvis sub- 

 cequalibus ; latere antico elevato, excavato, postico elliptico curvato; valvis costulis radi- 

 antibus angustis, rotundatis, regularibm, sed undulatis et granulatis ; ititerstiis duplo 

 latioribus subtillissime transverse striatis, striisque regularibus instructis. 



Shell elongated, convex, very oblique ; umbones small, pointed anterior ; auricles 

 small, nearly equal ; anterior side very convex, with a steep, excavated border ; posterior 

 side curved elliptically ; the entire surface has delicate but rounded, elevated, and finely 

 knotted radiating costae, gently waved and separated by interstitial spaces twice the 

 breadth of the costae ; the spaces have very fine, regular, and closely arranged transverse 

 striations; the plications of growth are few, but become prominent near to the lower 

 border. 



One of the most elongated and oblique of the Jurassic Limae. The general figure and 

 ornamentation would much resemble Lima ovalis, Sow., if the convexity of the anterior 

 side were not much greater, and the costse more elevated, in the Cornbrash shell ; the 

 striations are so densely arranged that the spaces do not present a punctated aspect, as is 

 usually seen when the striations are more distant, and larger. 



Dimensions. Length, 20 lines; breadth, 12 lines; diameter through both the valves, 

 10 lines. 



Geological Position and Locality. The Cornbrash -of Scarborough, in which it is 

 abundant. 



MODIOLA GIBBOSA, Sow. Tab. XXXIII, figs. 11, 11 a. 



MODIOLA GIBBOSA, Sow. Min. Con., t. 211, fig. 2. 



RENIFORMIS, Sow. Ib. fig. 3. ? 



D'Orb. Prodr., i, p. 282. 

 GIBBOSA, Mor. Cat id., 1854, p. 210. 



Testa elongato-ovato, convexa subreniformi umbonibus curvatis acutis sulco obliquo 

 antico ; latere antico in/erne sinuato, latere postico elliptico curvato ; lateribus plicis mag nits 

 concentricis distantibus. 



Shell ovately elongated, very convex ; umbones pointed, curved forwards j an oblique 

 sulcation proceeds downwards and forwards to the lower part of the anterior border, which 



