OF FOSSIL - SHELLS, 8cc. 



tufe prickles towards the extreme part of the margin, and others 

 more acute at diftances on the moulders, the beak as if cut off. 

 From the fliore of the brook at Simonburn. 



17. A fmgle valve of a fmall echinated OJlrea of a longer fhapc, 

 with a truncated beak. Tire prickles are obtufe, and at irregular 

 diftarices. From the bank of iron-fhiver above the bridge at Si- 

 monburn. 



1 8. A fmgle valve of a very fmall, fmoorhf OJlrea of a round 

 convex fhape, and a truncated beak. From the fame bank, where 

 there are confiderable numbers of them between the lamina of the 

 fliiver. They are of a yellowifh-white, and always found of the 

 fame fize and colour, free from blemimes-. 



Thefe five are varieties of the great, round, convex OJlrea. 



19. An oblong OJlrea with both valves, flriated lengthways, with. 

 a broad furrow down the middle of the under valve. From a 

 limeftone-quarry near Nunwick. It is a variety of the common 

 oblong fpecies, and feems to have been bruifed in its recent 

 ftate. 



20. A fmgle valve of the fmall 'falcated or hooked OJlrea (y ). It is 

 flriated lengthways ; the beak, and extremity inflected, or turned 

 inwards, forming a kind of half-round. In iron-ftone from the 

 clay-bank above the bridge at Simonburn. 



21. A fmgle valve of a large falcated or hooked OJlrea. It has a 

 broad furrow down the middle, and fmall flrise on each fid*.. It 



(y) Rondelet. de Fife. Mort. Northampt. 193. tab. 3. fig. i. 

 Oftreum minus falcatum. Lh. Lith. Brit. n. 451. 



is 



