DESGKIPTION OP SPECIES— FILICES. 59 



Oymnogramnia Ilaydcnii, Lesqz. 



Plate V, Figs. 1-3. 



Gymnogramma Haydenii, Lesqx., Annual Report, 1871, p. 295. 



Frond bi-tripinnatifid ; pinnce long, lanceolate, obtusely pointed, pinnately divided to near tho 

 rachis in oblong-lanceolate, obtusely pointed lobes ; the lower ones distantly dentate, the upper ones 

 more or less distinctly crenate ; rachis narrow ; middle nerve thin ; lateral veins close, at an acute angle 

 of divergence, dicbotomous. 



The three specimens figured give a tolerably good representation of the 

 form and of the characters of a pinna of this fine species. These pinnae were 

 evidently very long, gradually tapering to the point, the lobes becoming 

 shorter and proportionally narrower, though distinct, to the base of the ob- 

 tusely pointed terminal pinnule. The largest lobes, oblong, linguiform, are 

 distantly dentate, while in ascending, the marginal divisions, gradually effaced, 

 are merely crenate and the upper ones entire ; Ihey are joined in acute sinuses 

 a little above the narrow rachis, and slightly decurrent. As the substance 

 of the Fern is thick, coriaceous, the veins, when the epidermis is not destroyed 

 by maceration, are not very distinct, the middle one being often effaced and the 

 division of the lateral veins here and there obsolete. These are thin, nearly 

 straight in passing to the borders at an angle of 30° to 40° from the midrib, 

 join the main rachis between the pinnules, preserve the same direction, and 

 are dichotomous, generally forking twice. The largest lobes, as seen in fig. 

 2, are six centimeters long, one and a half centimeters broad in the middle, 

 where they are somewhat enlarged. The division of the veins is seen in fig. 

 2 a enlarged. The surface of the pinnee is covered by particles of what 

 resembles a pulverulent matter hardened into coal. I do not know of any fossil 

 species to which this one might be compared. Sphenopteris {Gymnogramma) 

 Blomstrandi, Heer (Flor. Arct., i, p. 155, pi. xxix, figs. 1-5), has only a distant 

 likeness by the outlines of its lobes, but is totally different by its nervation, 

 etc. This fossil Fern has a higher degree of affinity to Gymnogramma tar- 

 tarea, Desv., a common species of the present flora of Tropical America, 

 especially related to some of the varieties obtained by cultivation. 



Habitat. — Divide between the source of Snake River and the southern 

 shores of Yellowstone Lake {Dr. F. V. Hayden). 



