306 :\iESOZoic flokas of united states. 



midrih. This appearance is well shown in Xathorst's fifi. \)n. pi. i. Tiie 

 help of a lens is necessary to show this feature. The same figure of 

 Xathorst shows well the raised line in the middle of the upper face of 

 the midrib, on each side of which the bases of the segments are attached. 



The Geyser specimens show some leaves larger than any previously 

 described. The largest segments given for plants from other localities 

 hnxe a length of 8 mm., but some found in the Geyser beds detached 

 from the midrib show a length of 26 mm. Such a segment is shown in 

 PL LXXII, Fig. 17. These largest segments are alw^ays found detached. 

 Fig. 18 gives a fragment of a leaf of medium size with the segments very 

 uniform in size and shape. Fig. 19 represents a fragment of the largest 

 size found with detached segments. Fig. 20 gives a fragment of one of 

 the smallest leaves. On it the segments are unequal in width and the 

 nerves are very distinct. Fig. 21 shows a fragment of a small leaf with 

 the lamina almost entire. Only one division of it is shown on the right 

 side of the midrib and two on the left side. It is not certain that even 

 this segmentation is not due to the accidental splitting of the lamina 

 from pressure. 



This plant is found in Ixjth Professor Ward's and Mr. Weed's collec- 

 tions. In the latter there were a few small fragments that were noted 

 in the preliminary report as agreeing well with Angiopteridium sirictinerve 

 of the Potomac. A comparison of them with the very numerous and 

 well-preserved specimens of Nilsonia schaumburgcnsis found in Professor 

 Ward's collection showed that they are the w^idely detached segments 

 of that plant. PI. LXXII, Fig. 20, represents the best specimen collected 



by Mr. Weed. 



Genus ZAMITES Brongniart. 



Zamites akcticus Goppert. 



PI. LXXIII, Frgs. 1-6. 



1S64. Zamites arcticus Gupp. : XLI. Jahiesber. d. Schles. Gcs. f. vatorl. Cult., 



p. 84 (noineu). 

 1S66. Zamites arcticus Giipp. : Neues Jahrb. f. Miii.. etc., 1866, p. 134, pi. ii, figs. 9, 10. 

 1885. Zamites sp. Dn.: Trans. Eoy. Soc. Canada, Sect. IV, Vol. Ill, p. 7, pi. i, fig. 4. 

 1898. Zamites Weedii Font, in Weed & Pirsson: Eighteenth Ann. Rep. U. S. Geol. 



Surv., 1896-97, Pt. Ill, p. 481. (Pi. LXXIII, Figs. 1, 4.) 



A large number of imprints of a cycad were fovmd at the Grafton 

 and Geyser localities, wliich I can not by any essential features distinguish 



