1847.] BUNBURY ON FOSSIL PLANTS FROM EASTERN VIRGINIA. 285 



culiarities it agrees well enougli with Brongniart's figures and descrip- 

 tion of C. arenaceus, of which however the characters appear to be 

 somewhat obscure and ill-defined. 



This Richmond Calamite varies much in size, and often attains to 

 much larger dimensions than those assigned by Brongniart to the 

 C. arenaceus, several specimens being as much as 6 inches in diameter, 

 and one above 8 inches. The coaly envelope, or supposed bark, is 

 very thin and extremely fragile ; where it is preserved, its surface ap- 

 pears nearly even ; in general it remains only in the furrows, which 

 are partly filled up with it. The surface of most of the specimens 

 (when they are not compressed) is much wrinkled and puckered, with 

 irregular transverse folds, apparently caused by vertical pressure, and 

 showing the substance of the stem to have been soft and pUant at the 

 time when petrifaction took place. This appearance has been noticed 

 by Ad. Brongniart, and is well-represented in his 16th plate, fig. 1. 

 The ridges, on the decorticated stem, are scarcely gV^^^^ broad, 

 convex and slightly keeled ; the furrows between them equally narrow. 



The European C. arenaceus seems to be one of the most common 

 and characteristic plants of the Gres bigarre, and occurs also in the 

 Keuper, but not, as far as I can learn, in any other formation. 



9. Calamites. 



Among the specimens from "Deep-run," near Richmond, there 

 are some portions of a slender Calamite, which at first sight appears 

 different from the preceding kind, as the ridges, though equally nar- 

 row, are flatter, and generally appear (as it were) double, a slight 

 furrow running along the middle of each ridge. But I find the form 

 of the ridges, in C. arenaceus, so variable even in different parts of 

 the same specimen (owing probably to the degree of pressure and the 

 direction in which it has acted), that I do not trust to this character 

 as a sufiicient distinction ; and I think it very probable that the slender 

 stems in question may be young plants of C. arenaceus. They are, 

 like that species, destitute of tubercles at the articulations, which are 

 a little contracted. 



10. Zamites obtusifolius. 

 (Rogers, Z.c. p. 312. t. 14.) 

 " From Blackheath, near Richmond." 



Several specimens, agreeing very well with Prof. Rogers's description 

 and figure. 



This and the next species have completely the habit of Mr. Morris's 

 genus Ptilophyllum, especially of Pt. acutifolium, but the leaflets are 

 not oblique and imbricated at the base, but attached by the whole 

 breadth of it, as in Pterophyllum. 



11. Zamites gramineus (n. sp.?). 



I am by no means sure that this is distinct from the preceding : it 

 may be merely a larger variety or older state of the same plant. The 

 leaflets however are much longer and narrower in proportion, and 

 taper more gradually towards the extremity. They are from 2 to 3 



VOL. III. — part I. X 



