646 Extraneous FOSSILS.

they are sometimes found greenish, blueissi, yellowish or whitish, and sometimes,though rarely, spotted with different colours.

They are found lodg’d and bedded in the strata of Stone in Germany, Italy, France,in the islands of the Archipelago, and in Syria, among the spines of Echini; but theyare no where so frequent as in England, there being with us very few quarries but af-ford more or less of them.

Of F OS SI LE SHELLS.

These make greatly the larger number of the animal bodies bury’d in the earth,and are the greatest ornaments of the cabinets of the curious, but they have of all theothers the least title to descriptions in this work, as they belong wholly to the animalkingdom, and are there to be describ’d from specimens much more fair and perfectthan can be found in the Foffile world.

Of these we have some remaining almost entirely in their native state, others arevariously impregnated with stony and other particles; in the place of others we havemere Spar or Stone, exactly expressing all their lineaments, as having been form’d whollyfrom them ; the Shell having been dissolv’d by very flow degrees, and this matter leftin its place; or the cavities in Stone, out of which the Shells had perissi’d, having beenafterwards fill’d nicely up with these substances, which could therefore appear in noother but the perfect form of the perissi’d Shell. In many places also we have masses ofStone form’d in various Shells, and these having, while in a fluid state, nicely andexactly fill’d the cavities of the Shells, must be after the Shells are perissi’d from theirsurfaces exactly and regularly of their internal figure.

The various species we find of these are in many genera as numerous as the knownrecent ones; and as we have not only in our island the Foffile Shells of our own ssiores,but those of many other very distinct ones; so we have also many very numerousamong us, which are the product of yet unknown, or at least unfearch’d seas andssiores.

Of the bivalve Fossil Shells, the fame with the several species now known upon ourown and other ssiores, the most frequent are the Pectunculi or Cockles, these we findFoffile in great abundance in the strata of Stone, and in some others. The most fre-quent and numerous of these are of the roundish and smooth kind; numbers of the spe-cies of which we find very frequently in Gloucestershire and Northamptonssiire. In theneighbourhood of Bath, in some parts of Yorkssiire, and about Peterborough and Nor-thamptonssiire, I have met with great numbers of the longer ssiap’d cockles, these areusually pretty deeply striated, sometimes furrow’d from the cardo to the end. Somefew of them are ridg’d across with large broad and prominent fasciæ ; and some bothtransversely and longitudinally streak’d with lines as fine as a hair. In many parts ofSomersetshire that kind call’d by authors Trigonella, is very common in the smallerspecimens ; and there are a few large ones some four or five inches round, all immers’din Stone. This kind of cockle approaches to a triangular figure, having a broad bottomto which it descends on both fides, almost in strait lines from the head or cardo. In manyparts of the fame county, and in Leicestershire, and indeed in almost all the other coun-ties of England, we have abundance of the more common kind of the shorter cockles; ofthese some are striated longitudinally, some transversely, and not a few both ways; andin some the lines are very fine and small, in others very broad: Many of the larger cocklesfurnissi us also with what authors call Bucarditœ ; these are a stony or other matter form’din the cavity of the Shells, and thence necessarily resembling in some sort a heart at cards.Tire Curvirostra of authors are also Shells of this kind, so nam’d from the beak standingnot in the middle of the Shell, but always inclining to one or the other side ; and the Hippocephaloides or Horse’s Head Stone of Dr. Plot, is a cast in a Shell of this kind of thenature of the Bucarditæ.

The oysterssiells are also very common with us ; about Woolwich we find vast plen-ty of the common kinds ; and the tree oyster, as it is call’d, distinguissiable by the in-dentings of its edges, is very frequent in Somersetshire, Yorkssiire, and many otherplaces in Stone. The Shell of the common oyster is found to vary much in shape in itsrecent state, and it has not less irregularities in the Fossil world ; and there are some va-rieties which may well be esteem’d distinct species. The Lapis Auricularis or Ear Stone ofDr. Plot , is a mere fossil oyster, and in Berkshire and some other counties, we meet

with