312 ON THE AGE OF THE 



the Pecop. ohtuaifoUa of the Yorkshire Oolite, as represented by 

 Lind. and Hutton, plate CLVIII, figs. 1 and" IG. According to 

 the description of these authors, however, the Yorkshire fossil is 

 a much smaller and more delicate plant than ours. 



Lycopodites Williamsonis. Brongn.^ Prodromus. 



Lycopodites uncifolius. Phillips's Yorkshire. 



The fossil impressions referred to this title, comprising difl'er- 

 ent portions of the plant, among which are the head or cone, 

 con-espond in almost every particular with the figure of Lycop. 

 imcifolius^ given by Lindley and Hutton, as copied from IVIr. 

 WilUamson. " The one, and sometimes two, strongly marked 

 ridges up the centre of each leaf," the " oppositely placed leaves, 

 with the smaller ones between," the scales upon the stems, the 

 cones with " the strongly marked rhomboidal spaces like scars," 

 the peculiar claw-like form of the leaf, especially where full 

 grown, are all distinctly exhibited in the Virginia fossil. Indeed 

 the only points in which it seems at all to differ from the figure of 

 L. uncifolius given by Lindley and Hutton, Eu-e, that it is smaller 

 in all its dimensions, has apparently a less scaly stem, and has its 

 small leaves less sharply pointed, and less curved than the York-? 

 shire fossil. Considering these minor differences as affording no 

 sufficient grounds for ranking it as a distinct species, when in 

 other respects the agreement is so striking, I do not hesitate to 

 regard it as either identical with the Lyivpodites uncifolius, or 

 as a species closely allied to that plant. 



ZaMITES OBTUSIFOLIUS. 



The beautiful fossil, which I propose to designate by this title, 

 is found along with the Lycopodites, above described, in a state 

 of good preservation, in a dark-gray argillaceous slate, not far 

 above the coal. It has the form of fragments of the leaf, or pin- 

 na, one of which, in my collection, though still incomplete, is 

 about eight inches long. The impression of the midrib is nearly 

 straight, gradually tapering towards the outer end of the pinna, 

 and irregularly and rather finely sti-iated. This, when widest, 



