DESCRIPTION OF SPECIES— FILIOES, G3 



idea of the form and mode of division of the pinnules, but evidently repre- 

 senting a species of this genus. The divisions are short and comparatively 

 broad, oblong, pointed, and distantly serrulate near the point. The secondary 

 veins are on a more open angle than in the former species, diverging about 

 40° from the middle nerve, more distant, and forking only twice, or even 

 once. This species has no relation to any fossil of the same genus, for no 

 fossil Lygodium has been described as yet with serrate or dentate lobes. In 

 the living Ferns, Lygodium venustum, Sw., may be compared to it. 



Habitat. — Top of gypsum series, Grand Eagle Junction {A. R. Mar- 

 vine). This formation is referable to group No. 1. 



Liygodiiiui Dcntoni, Lesqz. 



Plate LXV, Figs. 12, 13. 



Lygodium Dentoni, Lesqx., Annual Report, 1874, p. 309. 



Leaflets small, tripartite, with short obtuse divisions and broad sinuses; primary veins three, 

 from the base, distinct; secondary veins also very distinct, forking once or twice, close along the 

 borders. 



The leaflets, round truncate at the base, rapidly widen upward, and, 

 near the top, are tripalmately divided in short, very obtuse, entire lobes, 

 separated by very broad sinuses; the middle nerves, somewhat thick, are 

 joined at or near the base; the secondary veins, also comparatively thick and 

 very distinct, ascend at an acute angle of divergence, those between the lobes 

 nearly straight upward, the lateral ones more curving, all forking once or 

 twice, and becoming close to each other along the borders. This species 

 is intimately allied to Lygodium exguisilum, Sap. (fit., iii, 2, p. 88, pi. i, 

 fig. 13), of the Grypses of Aix, a species differing by the secondary ner- 

 vation, more simple, the veins more distant along the borders, and the 

 leaflets merely bifid. This last character is, however, of little importance, for 

 the only specimen figured by the French author bears, on both sides of the 

 leaflets, short obtuse lobes like those of a tripartite or quadripartite pinnule 

 before its full development. In our species, the leaflets are somewhat larger, 

 two to three and one-half centimeters broad between the points of the lateral 

 lobes, which are one and a half to two and a half centimeters long, and as 

 broad as long. 



Habitat. — Green River group, near the mouth of White into Green 

 River, Utah (Prof. William Denton). 



