Maeyland Geological Survey 349 



doctenis.^ This is in many respects very close, if not identical, with 

 Ctenopsis, and if the former can be shown to have the double vascular 

 strands in the pinnules such as characterize the latter genus, the term 

 Ctenopsis will possibly have to be abandoned. 



Ctenopsis latifolia (Fontaine) 

 Plate LV, Figs. 1, 2 



Ctenophyllum latifolium Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 



1889, p. 175, pi. Ixviii, figs. 2, 3. 

 Podozamites grandifolius Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 



1889, p. 180, pi. Ixxxii, fig. 2; pi. Ixxxiii, fig. 5 (non other references 



under this name). 

 f Ctenophyllum latifolium Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., 



vol. xlviii, 1905, p. 255, pi. Ixvii, fig. 10. 



Description. — Frond very large and wide-spreading; length of pinnae 

 not disclosed, width in the same region of the frond variable, ranging 

 from 37 nun. to 35 mm. ; pinnules alternate, going off in the lower part 

 of the leaf at a large angle, in the upper portion becoming much more 

 oblique, attached by the entire width of the widened base, which is 

 decurrent and meets the expanded base of the adjacent pinnules, forming 

 a broad rounded sinus; those of the upper portion of the frond united 

 more and more, all curved slightly upward toward the summit of the 

 frond; tips of the pinn^ not seen; veins slender, going off obliquely at 

 their insertion in the lower and middle portions of the lower pinnules, 

 but nearly at right angles in the upper portions, and all turning strongly 

 outward to enter the pinnules; the veins fork usually at their insertion; 

 occasionally but rarely they fork farther from the rachis. 



These magnificent eycad fronds are extremely rare, although it is by 

 no means certain that the plant which bore them was equally rare in the 

 earlier Potomac flora. A large part of the frond is said to have been 



^ Seward, The Jurassic Flora of Sutherland, Trans. Roy. Soc, Edinb., vol. 

 xlvii, pt. iv, 1911, p. 691, pi. iv, figs. 62, 67, 69; pi. vii, figs. 11, 12, 17; pi. viii, 

 fig. 32; pi. X, fig. 45. See particularly pi. vii, fig. 62, and pi. x, fig. 45, of 

 Pseudoctenis latMensis Seward. 



