284 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 14, 



angle of more than 50°: these are about as broad as the main rachis 

 (rather more than -^ inch) ; their surface nearly flat, but in some 

 instances the central part is slightly raised above the margin, so as to 

 have the appearance of a midrib ; they are again pinnated or pinnati- 

 fid, but in an irregular manner, with short pinnules or lobes placed 

 at very unequal distances ; and their edges are everywhere beset (as 

 well between these lobes as along them) with the supposed heaps of 

 fructification, which form short oblong spots. These are converted 

 into coal ; but I cannot discover in them any distinct structure. 



The imperfect state of the specimens leaves in great obscurity the 

 real nature and affinities of this curious fossil. I can trace no con- 

 nexion with any better-known form, for the fragments occur separate 

 and unmixed with anything else. Farther observations, in the mines 

 themselves, may possibly throw some light on its structure. I think 

 there is little doubt of its belonging to the tribe of Ferns ; but as it 

 is not referable to any genus hitherto established, and can hardly, as 

 yet, be satisfactorily characterized as a genus, it may be left for the 

 present under the vague and comprehensive name of Filicites. 



7 . Equisetum columnare. 

 (Ad. Brongn. Veg. Foss. v. i. 115. t. 13.) 



" From Blackheath, near Richmond." 



Numerous specimens, in good preservation, from several different 

 pits about Blackheath. They agree so perfectly with Brongniart's 

 description and figures, as to leave no doubt of the identity of the 

 Virginia plant with that of Whitby, as already determined by Prof. 

 Rogers. On one of the large uncompressed specimens, there is an 

 appearance of the origin of a branch, which seems to have sprung from 

 one of the joints of the stem. Nothing of the kind is noticed by 

 Brongniart. 



The Equisetum columnare is well known as a characteristic fossil 

 of the inferior oolite ; but it is said by linger* to occur also in the 

 Keuper near Stuttgard. 



8. Calamites arenaceus. 

 (Rogers, in Report of Assoc, of American Geol. p. 304.) 



Qu. also C. arenaceus, Brongn. ? 



C. Suckowii, var. ^, Brongn. Veg. Foss. 125. 1. 16. f. 1. 



The specimens of this Calamite, from the pits in the neighbour- 

 hood of Blackheath near Richmond, are so numerous, as to prove it 

 to be the most common fossil plant of that locality. It is certainly 

 the C. arenaceus of Prof. W. B. Rogers (in the paper already quoted); 

 but it is also the plant described and figured by Brongniart as the 

 variety h. of C. Suckowii. It is not easy to say what really constitutes 

 a specific distinction among the Calamites ; but in the remarkable 

 narrowness of its ridges, and the apparently constant want of tubercles 

 at the articulations, our plant differs so much from C. Suckowii, that 

 it appears to be as distinct as any of the genus. In these same pe- 



* Synopsis, p. 27. 



