BIVALVIA. 9 



Shell equivalve, suborbicular, convex ; auricles large, unequal, and finely striated; costae 

 large rounded, radiately diverging (about 40 in the circumference), interstitial spaces 

 narrow and conformable. 



The anterior auricle is very large, the posterior one small; the costae are regular, rounded, 

 and closely arranged, the convexity of the valves is so considerable that the diameter 

 through both is nearly equal to the lateral diameter. The general aspect is sufficiently 

 distinct from all the associated species ; Pecten arcuatus, which has the costae similarly 

 disposed, has a figure much less convex and orbicular, and the interstitial spaces are 

 punctated. 



Locality. This species is not unfrequently found in the white stone of Bussage and 

 Eastcombs, bordering upon Bisley Common, and we are not aware that it has been found 

 at any other locality. 



The name from Mr. S. P. Woodward, of the British Museum, to whom it is dedicated. 



PECTEN PEKEGRINUS. Tab. I, fig. 14. 



? Var. of PECTEN VAGANS, Sow. 



Testa intequivahi, ovato-orbiculari, auriculis magnis incequalibus costellatis ; valvd 

 sinistrd subpland, costis radiantibus angustis, plicatis (circa 9), intervallis incequalibus, 

 nonnunquam costulis interstitialibus evanescentibus hinc et inde dispositis. Valvd dextrd 

 convexd lamellis tenuissimis concentricis imbricatis, et sulcis magnis radiantibus (circa 10). 



Shell inequivalve, ovately orbicular, auricles large, unequal and costellated ; left valve 

 rather flattened, radiating costse (about 9) arranged at irregular distances, narrow, nearly 

 equal, with small and irregular plications; there are likewise two or three small interstitial 

 lines or elevations upon the anterior side of the valve. Right valve convex, with very fine 

 concentric and imbricated lamella?; radiating sulcations (about 10) large and rather 

 irregular. 



The irregular distances at which the four anterior costse of the left valve are placed, 

 their narrow figure and small plications, will serve to distinguish it from Pecten vagans, 

 the great convexity and obliquity of the other valve will equally distinguish it from Pecten 

 jibrosiis. It occurs somewhat rarely in the shelly beds of the Great Oolite. 



Localities. Minchinhampton and Bisley Commons. 



PECTEN RETIFERTJS. Tab. I, fig. 15, 15<z. 



Testa ovato-orbiculari, convexo-pland, auriculis magnis sudesqualidus reticulatis; lineis 

 radiantibus clatis numerosis, irregularibus, aliis concentricis et elatis paucioribus decussatis. 



Shell ovately orbicular, moderately convex, auricles large, nearly equal and reticulated; 

 with radiating lines, elevated, numerous and somewhat irregular, crossed by others elevated 

 and rounded but of unequal size and more distant. 



The surface is crossbarred and somewhat rugose, the concentric lines in the more 



2 



