330 PROCEEDINGS OF THE NATIONAL MU8EUM. vol.41. 



The latter species is on the whole a larger form with less elongate 

 and more triangular pinnge, and the pinnules have more entire mar- 

 gins, the lobes or teeth being rounded and not angular. The veins 

 are also more numerous. 



Occurrence.—PATXJXiii^T formation: Fredericksburg, Dutch Gap, 

 Potomac Run, Telegraph Station (Lorton), Virginia. 



Collections. — United States National Museum. 



ONYCfflOPSIS PSILOTOIDES (Stokes and Webb) Ward. 



Hymenopteris psilotoides Stokes and Webb, Trans. Geol. Soc. London, ser. 2, vol. 1, 

 1824, p. 424, pi. 46, fig. 7; pi. 47, fig. 2. 



Sphenopteris mantelli Brongniart, in Mantell, Illus. of the Geol. of Sussex (rev. ed.), 

 1827, p. 55, pi. 1, figs. 3a, b; pi. 3, figs. 6, 7; pi. 3^, fig. 2.— Schenk, Palaeont., 

 vol. 19, 1871, p. 208, pi. 23, fig. 1-8; pi. 4, fig. 6 (?); vol. 23, 1875, p. 158, 

 pi. 28, fig. 12.— Heer, Contr. Flora Foss. Portugal, 1881, p. 12, pi. 11, figs. 

 1-5; pi. 12, figs. 2b, 266.— Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 

 1890, p. 91, pi. 1, figs. 1, 2.— Saporta, Flora foss. Portugal, 1894, pp. 72, 

 124, 157, pi. 15, figs. 8-12; pi. 18, fig. 5; pi. 23, figs. 1, 2, 8; pi. 28, fig. 2; 

 pi. 29, fig. 1; pi. 30, figs. 9, 10; pi. 31, figs. 1, 2. 



Onychiopsis mantelli Seward, Wealden Flora, pt. 1, 1894, p. 41, figs. 4, 5 on p. 50; 

 fig. 6 on p. 52, pi. 2, fig. 1; pi. 13, figs. 1-4; Flora Weald, de Bernissart, 

 1900, p. 15, pi. 1, figs. 17-19; pi. 2, figs. 20, 21; Ann. S. Afr. Mus., vol. 4, 

 1903, p. 5, pi. 1; pi. 5, fig. 1. 



Thyrsopteris insignis Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 127, pi. 

 39, fig. 4; pi. 40, fig. 1; pi. 41, fig. 6; pi. 43, figs. 1, 2, 4; pi. 53, figs. 1, 3.— 

 Fontaine, in Ward, Monogr. U. S. Geol. Surv., vol. 48, 1906, p. 521. 



Thyrsopteris insignis angustipennis Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, 

 p. 128, pi. 43, fig. 2. 



Thyrsopteris angustifolia Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 131, 

 pi. 44, fig. 4; pi. 45, fig. 3; pi. 48, fig. 2; pi. 49. figs. 3, 4; pi. 55, fig. 2; pi. 58, 

 fig. 8.— Fontaine, in Ward, Monogr. U. S. Geol. Sur., vol. 48, 1906, p. 516. 



Thyrsopteris microphylla Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 151, 

 pi. 45, figs. 1, 2, 4, 5. 



Thyrsopteris rarhiervis Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 123, 

 pi. 26, figs. 6, 7; pi. 43, figs. 4-6; pi. 44, figs. 1, 2, 5; pi. 49, fig. 2; pi. 169, 

 figs. 6, 7.— Fontaine, in Ward, Monogr. U. S. Geol. Surv., vol. 48, 1906, 

 pp. 225, 484, 491, 514, 517, 518, 519, 521, 528, 548, 558, pi. 65, figs. 2-4; pi. 

 113, figs. 2, 3. 



Thyrsopteris dentifolia Fontaine, in Ward, 19th Ann. Kept. U. S. Geol. Surv., pt. 

 2, 1899, p. 660, pi. 161, figs. 6-9. 



Onychiopsis psilotoides Ward, in Fontaine, in Ward, Monogr. U. S. Geol. Surv., vol. 

 48, 1906, p. 155 (name only). — Fontaine, in Ward, Monogr., U. S. Geol. 

 Surv., vol. 48, 1906, pp. 506, 518, 528, pi. Ill, fig. 4; pi. 113, fig. 1.— 

 Knowlton, in Diller, Bull. Geol. Soc. Amer., vol. 19, 1908, p. 380. 



Description. — The following description was given by Seward in 

 1894: 



Frond tripinnate, ovate lanceolate, rachis winged and prominent; pinnae lanceolate, 

 alternate, approximate, given off from the main rachis at an acute angle. Pinnules 

 alternate, narrow, lanceolate acuminate, uninerved, of nervation type Coeopteridea 

 (Luerssen, in Rabenhorst 'a Krypt. Fl., vol. 3, p. 11); the larger ones serrate and 

 gradually passing into pinnae with narrow ultimate segments. Fructification in the 

 form of sessile or shortly stalked linear ovate segments with rugose surfaces, and ter- 

 minating usually in a very short awn-like apical prolongation. 



