O F F O S S I L - S H E L L S, &c. io? 



laft mentioned quarry, fome of them are of a vaft fize, tinned 

 with red. Their general colour is cinereous. We never find 

 them with double valves. Sometimes many of them include one 

 another. Groups of them are frequent in ftone with Entrocboi, 

 and the lithoftrotion, on the more of the brook at Simonlurn. Thefe 

 are more neat and handfome than any I have obferved in quar- 

 ries ; parting eafily from the ftone with a flight ftroke of a 

 hammer. We have them in the clay-bank above the bridge at 

 Simonburn, with other fhells. There they are fo tender and fragil, 

 that it is rare to get one out intire. In the air they acquire a con- 

 fiderable hardnefs* 



Two phyficians, Dr. Home of Berwick upon Tweed, and Dr. Cay 

 of Neivcaftle upon jyf,ufed this fhell very fuccefsfully in nephri- 

 tic cafes, and in curing fuch as were afflicted with the gravel. 

 They gave it in fine powder, mixed with about a third part of 

 Flo. CammomeL the dofe from half a dram to a dram in white 

 wine (x). 



14. A fingle valve of an Ojlrea of a round convex fhape, with 

 a broad furrow down the middle from the Cardo to the extre- 

 mity. From the more of the brook at Simonburn. We have it alfo 

 in limeflone at Chipchace. 



15. A fingle valve of an Ojlrea of a round convex fhape, with 

 longitudinaly?rz>, protuberated round the extreme margin after a 

 fmgular manner, forming a kind of froft-work. From the more 

 of the brook near Nunivick. 



1 6.- A fingle valve of a miall echinated Ojlrea, of a round con- 

 vex fhape, with a truncated beak. It has a double feries of ob- 



(x) Ph. Tr. No. 25. 



P 2 tllfc 



