316 • PR0CEEDWG8 OF TSE! PAi'lONAL MtJSSVM. toL. 41, 



oblong or ovate, obtuse, slightly falcate, and usually with a some- 

 what rounded and slightly constricted base, separate, more or less 

 remote, in some specimens those of the lower pinnae with crenate 

 margins, those of the upper ones entire, passing in the middle part 

 of the frond through pinnules with undulate margins. Leaf-substance 

 thick and leathery. Midvein of the usual Cladophlehis type, that is, 

 strong at base and dissolving into branches at the summit; lateral 

 nerves of the crenate and undulate pinnules in groups in each tooth, 

 composed of a midvein which sends off alternate simple branches, or 

 else of forked veins with one of the branches forking again; those of 

 the pinnules with entire margins usually once forked, all quite dis- 

 tinct; fertile specimens rare, Sori very large, elliptical or reniform in 

 shape, and distributed in two rows, one on each side of the midvein, 

 attached to the summit of the upper branch of a furcate nerve. 



This species is quite generally distributed throughout the Potomac 

 formations, although there is but one recorded occurrence from the 

 Arundel formation. It is abundant in the Patuxent formation at 

 Fredericksburg and outside the Maryland- Virginia area it has been 

 recorded from the Kootenai formation of Montana and British 

 Columbia and the Shasta of the Pacific coast province. 



The sterile and fertile pinnae are closely similar in outline and 

 venation, the former being much more abundantly represented than 

 the latter. They are both very similar to those of Clado'pTilebis parva 

 Fontaine and may be compared with a number of European and 

 Kome species of Clado'phlebis , Alethopteris , Pecopteris, etc. 



Occurrence. — Patuxent formation: Fredericksburg, Dutch Gap, 

 Telegraph Station (Lorton), Virginia; Broad Creek, Maryland. 

 Arundel formation: Arlington, Maryland. Patapsco formation: 

 Chinkapin Hollow, Virginia. 



Collections. — United States National Museum. 



CLADOPHLEBIS PARVA Fontaine, emended. 



CladophleUs parva Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 73, 



pi. 4, fig. 7; pi. 6, figs. 1-3.— Fontaine, in Ward, 19th Ann. Rep. U. S. Geol. 



Surv., pt. 2, 1899, p. 657, pi. 160, fig. 18; Monogr. U. S. Geol. Surv., vol. 48, 



1906, p. 225, 280, 510, 538, pi. 65, figs. 5-8.— Knowlton, in Diller, Bull, 



Geol. Soc. Amer., vol. 19, 1908, p. 386. 

 CladophleUs inclinata Fontaine, in Diller and Stanton, Bull. Geol. Soc. Amer., 



vol. 5, 1894, p. 450.— Fontaine, in Stanton, Bull. 133, U. S. Geol. Surv., 



1896, p. 15. 

 Cladophlebis, sp., Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 81, pi. 



26, fig. 15. 

 Aspidiuvi heterophyllum Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 



96, pi. 14, figs. 1-5; pi. 15, figs. 1-5.— Fontaine, in Diller and Stanton, Bull. 



Geol. Soc. Amer., vol. 5, 1894, p. 450.— Fontaine, in Stanton, Bull. 133, 



U. S. Geol. Surv., 1896, p. 15. 

 Dryopteris heterophylla Knowlton, Bull. 152, U. S. Geol. Surv., 1898, p. 92.— 



Fontaine, in Ward, Monogr. U. S. Geol. Surv., vol. 48, 1906, pp. 483, 650, 



pi. 115, figs. 7, 8. 



