426

shows that Mr. Da Costa was mistaken ; the specimens, of whichhe speaks, had, instead of the smooth, or the' striated surface ofgramma , studs, or tubercules, over the greatest part of its surface*.But Dr. Woodward mentions another specimen, apparently of thereed tribe, which was originally two feet long.

The same circumstance is observable in these fossils, as has beenmentioned when speaking of the vegetable remains in the ironnodules. Very frequently, indeed, will the bituminizating processhave proceeded to the formation of the black bitumen, or jet, andcanel-coal; such has been the case in the specimen already referredto, Plate III. Fig. 3, several particles of black bituminous matterbeing yet adherent, at the transverse sulcus or joint.

The specimens of Dr. Woodward, referred by Mr. Da Costa tothe reed tribe, are undoubtedly similar fossils to that describedPlate III. Fig. 1, and which is indeed, in many respects, a mostsurprising and interesting fossil. These fossils differ much in theirlength from the size of that which is here depicted, to those men-tioned by Dr. Woodward : one of which was five feet, and the othersix feet and a half long-f. They also differ very much in their thick-ness, the most common size being less than that of a man's arm;but Mr. Martin observes, that they are sometimes met with of fouror five times that size. The substance of these fossils is either afine grit-stone, with small micaceous particles, or a stone in whichno grit appears; but such a mixture of argillaceous and siliciousearth as approaches to a jasper; the colour of both these kinds ofstones varying, with different shades, from the lightest, to almost thedarkest brown. The general figure of this fossil is that of a long,irregular, and compressed cylinder; the surface of which is prettythickly beset, in quincunx order, with holes, from the bottom of

* Catalogue of English Fossils, Part II. p. 104. q. 1.

t Ibid. Part I. p. 104. q. 1. and Part II. p. 59. h. 34.