314 ON THE AGE OF THE 



latter antlior, adding the specific name obtusifolms, as descrip- 

 tive of the mode of termination of the leaflets. - The propriety of 

 referring it to tiiis genus will at once appear on comparing the 

 above description of the fossil and the accompanying figure, 

 with that part of Sternberg's definition of the genus which relates 

 to the leaves, comprised in the following words : 



" Folia pinnatifida, vel pinnata, pinnis distichis, sessilibus ad- 

 natisve, laciniisqne integ-errimis nervosis, nervi plures, paralleli, 

 in basi pinnaru?n vel laciniariim juxta deposit^ 



It will be seen that the Zamites obtusifolms, as above charac- 

 terized, bears a close resemblance, in most particulars, to the fossil 

 figured and described by Brongniart, under the title of Filicites 

 vittarioides, and since described by Sternberg as Zamites blech- 

 noides. Vide Hist, des Veg. Fos : Liv. 11, p. 391, and Stern- 

 berg's Versuch, &c., part 7 and 8, p. 200. Though this fossil is 

 spoken of by Brongniart as having been sent to him by Prof. 

 Silliman, from the coal-field of Eastern Virginia, I have been 

 unable to find it anywhere in this region. The points in which, 

 according to the description of Brongniart it diti'ers from Z. obtu- 

 sifoliiis, are the confluent form of the pinnules where they join 

 the midrib, and the invariable presence of but tico nerves in each 

 pinnule. 



Zamites tenuistriatus. 



The impressions of this fossil, which I have thus far met with, 

 are imperfect and rather obscure, consisting of disjoined leaflets 

 and incomplete fronds. They are, however, sufficiently distinct 

 to show the pecufiar form of the leaflets, their mode of attach- 

 ment to the midrib, and their nervation. 



The leaflets, varying from three fourths of an inch to one inch 

 in length, and from one eighth to one tenth of an inch in breadth, 

 where widest, are sharply elliptical at base, attached dii-ectly to 

 the midrib, and taper with great regularity from the place of 

 greatest width (about one fourth the whole length from the mid- 

 rib) to their termination. The nervures are parallel, numerous, 

 and so delicate as to be but obscurely traceable on most of the 

 impressions. 



