Maryland Geological Survey 273 



Onychiopsis latiloba (Fontaine) 

 Plate XXXIII, Figs. 1, 2 



Sphenopteris latiloha Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 90, pi. XXXV, figs. 3-5; pi. xxxvi, figs. 4-9; pi. xxxvli, fig. 1. 

 Thyrsopteris brevipennis Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 



1889, p. 124, pi. xxxiv, fig. 3; pi. xxxvi, fig. 2; pi. xxxvii, figs. 3, 9; 



pi. xxxviii, fig. 1; pi. xli, fig. 4. 

 Thyrsopteris divaricata Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 



1889, p. 125; pi. xxxvii, figs. 5-8; pi. clxx, fig. 1. 

 Thyrsopteris crenata Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 127, pi. xxxix, figs. 1, 2. 

 Thyrsopteris drevipennis Fontaine, 1899, in Ward, 19th Ann. Rept. U. S. 



Geol. Surv., pt. ii, p. 662, pi. clxii, fig. la. 

 Sphenopteris latiloba Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., vol. 



xlviii, 1905, pp. 281, 479, 491, 511, 534, 557. 

 Thyrsopteris divaricata Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., 



vol. xlviii, 1905, pp. 504, 511, 517, 521. 

 Onychiopsis latiloba Berry, 1911, Proc. U. S. Natl. Mus., vol. xli, p. 332. 



Description. — Frond large tripinnate; principal rachis very stout, 

 sometimes Avinged. Leaf-substance thin but coriaceous. Primary pinnae 

 opposite or subopposite with a stout, rigid rachis, which is often some- 

 what fiexuous; ultimate pinn^ remotely placed, very short, decurrent, 

 passing towards the summit of the principal pinna or of the frond 

 through lobed pinnules into entire ones. Pinnules somewhat remotely 

 placed, cuneate at base, those in the lower part of the frond cut more 

 or less deeply into oblong acute to obtuse lobes, passing towards the 

 tips of the ultimate pinnae into lobed pinnules like those of the upper 

 part of the frond, and at the tips into ovate or oblong lobes and teeth. 

 In the upper part of the frond they are elliptical, three lobed, or entire. 

 All the pinnules and segments are broad. The ultimate pinna3 and the 

 pinnules of the lower part of the frond usually terminate in three lobed 

 segments or in broad, elliptical pinnules. The veins are copiously 

 branched,' diverging flabellately into the lobes and teeth, and are very 

 distinct and strong, although not coarse. 



This is a fine, large species, probably arborescent, and quite distinct 

 from the other species of OnycMopsis. It is common throughout the 

 Potomac but rather less abundant in the Patapsco formation than in 

 the older beds. It has been recorded from the Lakota formation in the 



