300 Systematic Paleontology 



comian of Portugal. Heer described a species from the Kome beds of 

 G-reenland in 1874, but afterward transferred it to the genus Dicksonia. 



Scleropteris elliptica Fontaine 

 Plate XXXIX, Figs. 1, 2 



Scleropteris elliptica Fontaine, 1890, Mon. U. S. Geol. Survey, Vol. xv, 1889, 



p. 151, pi. xxviii, figs. 2, 4, 6; pi. xxix, fig. 1. 

 Scleropteris elliptica var. longifolia Fontaine, 1890, Mon. U. S. Geol. Surv., 



vol. XV, 1889, p. 152, pi. xxviii, fig. 7. 

 Scleropteris virginica Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 152, pi. xxviii, figs. 3, 5. 

 Ctenopteris integrifolia Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 158, pi. Ixii, fig. 2; pi. Ixv, fig. 3 (non Font, 1906). 

 Scleropteris elliptica Fontaine, 1906, in Ward, Mon. U. S. Geol. Survey, 



vol. xlviii, 1905, p. 511. 

 Scleropteris virginica Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., vol. 



xlviii, 1905, p. 484. 



Description. — Frond bipinnate or tripinnate, probably arborescent. 

 Main rachis stout, its branches rather slender and straight. Pinnae 

 alternate or subopposite, broadly linear in general outline. Pinnules or 

 segments lanceolate, becoming much reduced distad, directed upward ; 

 with an acute apex and a narrowed decurrent base which produces a 

 mnged rachis. Usually a single vein enters each pinnule, soon diverging 

 in a flabellate manner into several which are simple or fork once or twice 

 before their termination in the margin. In one specimen there appear 

 to be several veins entering a pinnule, suggesting the forms constituting 

 the genus Ctenopteris. The veins are all immersed and difficult to make 

 out with certainty. Texture coriaceous. The pinnules vary greatly in 

 size, reflecting the individual variation in the species and that due to 

 position on a single plant. Thus their dimensions range from 0.5 cm. 

 to 3.4 cm. in length, and from 1 mm. to 4 mm. in greatest width. 

 Where the pinnules are more or less elongated and slender the veins 

 approximate a parallel course. 



This species, which is seen to contain three supposed species described 

 by Prof. Fontaine, is not uncommon in the older Potomac, to which it is 

 confined, not occurring in the Arundel formation or outside the Mary- 

 land-Virginia area. 



