58 UNITED STATES GEOLOGICAL SURVEY— TEETIAEY FLORA. 



GYMNOGRAMMA, Desv. 



Oymnogramnia Gardneri, Lesqz. 



Plate IV, Fig. 2. 

 Pteris Gardneri, Lesqx., Annual Report, 1873, p. 393. 



Frond large, simply pinnate ; pinnae large, linear, broader in the middle, in rigbt angle to the 

 rachis, rounded to the base ; borders deeply undulate ; middle nerve broad, grooved in the middle, flat- 

 tened on the borders; veins in an obtuse angle of divergence, abruptly curving downward at the base, 

 or decurring to the rachis, forking once or twice, joined by anastomoses and forming by cross-branches 

 irregular, long areoljB. 



The large pinnae, three to three and a half centimeters broad in the 

 middle, where they are enlarged and broken, apparently lanceolate, with a 

 broad flat midrib, narrowly grooved in the middle, have entire but irregularly 

 undulate borders, and lateral veins at an open angle of divergence 70 to 80°, 

 thin, forking once near the base, sometimes twice, and here and there irreg- 

 ularly anastomosing by cross-veinlets. The substance is rather thin. I con- 

 sidered first this Fern as referable to Pteris, as some species of this genus 

 have pinnae of the same form, and the lateral veins sometimes anastomosing 

 as in Pteris grandifolia, Linn., which, however, shows this kind of division 

 of the veins only near the borders, and far more regular than in this species. 

 The genus Pteris has now two essential divisions: Heterophlehium and 

 Campteria; the first one has leaflets with lateral veins anastomosing toward 

 the margins, the second with veins connected at the base by arching vein- 

 lets. I supposed that the fragments described here might represent a section 

 intermediate between both, or with veins anastomosing in the middle of the 

 areas. But there is in Gymnogramma a species, G. Japonica, Desv., whose 

 characters are so evidently comparable to those of this fossil one that it seems 

 rational to admit it in the same genus. The Japan Fern has long, simple, 

 linear, oblong, acuminate pinnse, rounded at the base, the rachis flat on both 

 sides of the midrib, the veins close, forking once or twice, and joined by 

 cross-veinlets ; all this as in the fossil species. The comparison of speci- 

 mens shows the relation to be very close. 



Count Saporta informs me that quite recently a Fern has been discov- 

 ered in the Gypses of Aix, representing a species which he considers as iden- 

 tical with this, or at least closely allied. He is disposed to refer it to the 

 genus Chrysodium, a section of the Acrostichum. 



Habitat. — Roof of a coal-mine, Sand Creek, Colorado {A. Gardner). 



