32 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



PECTEN IN^EQUICOSTATUS, Phil. Tab. XXXIII, figs. 1, 1 a. 



PECTEN IN^EQUICOSTATUS, Phil. Geol. York., i, pi. 4, fig. 10. 

 I? Orb. Prodrome, p. 3/3. 



OCTOCOSTATUS, Roemer. Ool., p. 69, pi. 3, fig. 18. 



INJEQUJCOSTATUS, Mw. Cat. Brit. Foss., 1854, p. 176. 



Op-pel. Juraformation, p. 607. 



Testa ovato-acuta, convexa, longitudinaliter , 8 costata, concentrice lineata, costis con- 

 vexis latis sulcis conformibus in dorso Idnc inde dentatis, duobus mediis latioribus, lineis 

 exilibus confer tis sublamellosis auriculis sub&qualibus longitudinaliter lineatis. (Roemer pro 

 valva desstra.} Valva sinislra costis (8) angustis, elevatis rotundis asymmetricis, subnodosis, 

 interstiis latis irregulariter concentrice striatis. 



A convex, subaequivalve, acute-pointed Pecten, with large, nearly equal auricles ; the 

 surfaces of both the valves having irregular, concentric striations and several large folds of 

 growth. The right valve has broad, slightly elevated costse (8), which are unequal and 

 slightly defined towards the posterior side, separated by narrow and but little depressed 

 sulcations, which are distinct upon the inner surface of the valve ; the left valve has eight 

 narrow, elevated, but rounded costse, of which those upon the sides are small and 

 unsym metrical ; the intervening spaces are broad upon the middle of the valve, and very 

 narrow laterally ; the auricles are obliquely lineated. 



Geological Positions and Localities. Rarely in the Cornbrash and Kelloway Rock of 

 Scarborough, more commonly in the Coralline Oolite of Malton, but it is seldom well 

 preserved at either of these geological positions ; Roemer makes a similar statement 

 respecting its occurrence at Lindner Berges. 



PECTEN ARTICCLATCS, Schloth. Tab. XXXIII, fig. 12. 



PECTEN AKTICULATCS, Schloth. Petref., pp. 227, 228. 



Gold/. Petref., p. 47, tab. 90, fig. 10. 

 Roemer. Verst, p. 68. 



Testa ovato-acuta convexa, costis angustis acittis, subaqualilus cingulatis acuminatis, sul- 

 cis duplo latioribus concavis subtillissime transversim striatis, auriculis in&qualibus lamelloso- 

 lineatis costulisque virgatis. (Goldfuss.) 



Shell ovately pointed, convex ; radiating costse elevated, narrow, acute, more or less 

 unequal, with acute transverse lamellae ; interstitial sulcations wider than the costse, 

 concave, with delicate transverse striations ; auricles unequal, with 'radiating ribs crossed by 

 lineal lamella?. The more numerous ribs (about twenty-four), their irregularity and in- 

 equality, will distinguish it from P. vimineus, Sowerby, a species which abounds in the 

 Inferior Oolite. 



Geological Positions and Localities. Pecten articulatus occurs in the Cornbrash of 

 the Yorkshire coast, and more frequently in the Calcareous Grit and Coralline Oolite of the 

 same county. 



