666 PHILOSOPHICAL TRANSACTIONS. [aNNO \74Q. 



and narrow a little again at their end. Each division or leaf is bounded on each 

 side by a row of parallel ridges, which are accompanied also on each side of every 

 said row, with 2 other ranges of points or knobs ; all which rows do not meet or 

 close together at the lower end of the division, but leave a void unwrought space: 

 a row of larger irregular knobs runs through the midst of each leaf. From the 

 divisions between each leaf runs a rugged knobb'd pillar, joined to the edge : the 

 other parts between the leaves and the edge, are hollows, or void spaces. The 

 edge or limb is of a thick cylindric make, runs quite round the whole body, and 

 only has some signs of being disjoined at the one extreme of the length, or where 

 the aperture was ; the stone answering which is here extended a little cylindri- 

 <.'ally outward like an appendage, and was so formed by the stony matter being 

 too much in quantity for the shell, and so was protruded through the said fora- 

 men. On the outer edge of the limb, are some few irregular stony concretions. 

 The basis is flat, and is divided into 5 parts from the centre, which is one of the 

 foramens ; the other foramen being placed at one of the extremes of the length. 

 This foramen or centre is about the size of a shilling. The 5 divisions extend to 

 the utmost edge of the body, or quite over the limb, contrary to the divisions on 

 the upper part, which extend only to it. Each division is formed by a stony line 

 edged on each side with stony cylindrical bodies of the thickness of a pin, but of 

 different lengths, so as to appear like the teeth of a comb, or the gills of a fish ; 

 the interstices between all which is a rugged stony work, and hollows pervading 

 quite through the body to the upper part. 



The other echinite is of a dificrent species, though of the same genus, of a 

 heart-like shape, and about one third the size of the above described. This is 

 greatly copped, the apex lying very high, and the 5 divisions rurming nearly per- 

 pendicular down to the edge. The upper part of this is elegantly perfect ; the 

 work is nearly the same as on the other; only that, by the perfection this pre- 

 served is in, we observe that the rows of parallel ridges, which adorn each side of 

 each leaf or division, rise into a kind of arched work or bridge, made up of arched 

 cylindrical bodies, through which the middle row runs, joined or connected in a 

 long straight cylindrical stem, in a most curious and elegant manner. The basis 

 or under part of this specimen is very imperfect, and only seems to differ in the 

 centre being greatly excavated or concave, answering to the great copping or 

 height of the apex or upper part. This fossil also consists of a hard stony arena- 

 ceous substance like the other. 



From the inspection of the several hollows of these echinites, it is evident 

 that they were not immediately moulded in the shells, but were formed in cavi- 

 ties which those shells formerly filled in the rocks they were lodged in. The 

 rocks were apparently of a loosened arenaceous texture, and the water, &c. con- 

 tinually pervading them^ rotted and destroyed the inclosed shells, and bore 



