DESCEirXION OF SPECIES— FILICES. 53 



would be a terminal pinna. It seems, therefore, that tliese fragments are 

 mere leaflets. They are in size from eight to ten centimeters long, and from 

 one and a half to three centimeters broad, vvilh a narrow midrib, and tliick, 

 distinct veins, all under the same angle of divergence, G0°, simple or forking 

 once, and reaching the borders straight, or witliout deflecting upward or down- 

 ward. The borders, by contraction at the point of connection of the veins, 

 are slightly crenulate. This character is unlike that of tlic nervation of 

 Osmundii leaves, to which this Fern might be compared, by the Ibrm of the 

 leaflets, resembling those of plate iv, fig. 1. Taken for simple fronds, they 

 have a relation to Acrostichum latifoHum, Sw., var. alismcefoUum of Cuba, 

 which has the same type of nervation. As leaflets of a compound frond, they 

 are comparable io Acrostichuin cervmum, Sw., or Lomariopsis Wrightii, Mett., 

 both Cuban species also. 



Habitat. — Golden, Colorado. 



Ptcrls erosa, Lesqx. 



Plate IV, Fig. 8. 



Pteris erosa, Lesqx., Supplement to Annual Report, 1871, p. 12 ; Anntial Report, 1873, p. 392. 



Pinna) large, broadly lanceolate, taper-pointed ; border obtusely dentate toward tbe point, irreg- 

 ularly crenulate-laceralo in the middle ; middle nerve thick ; veins at an open angle of divergence, fork- 

 iug once or twice, slightly turned up in reaching the borders. 



The only specimen of this Fern figured here represents the point of a 

 large pinna, the fragment being five and a half centimeters long and three 

 centimeters broad toward the middle. The pinnae are near the point regu- 

 ularly obtusely dentate ; but lower the teeth become irregular in form and 

 size, and more or less deeply eroded. The veins are about at the same angle 

 of divergence as in the former species, to which this one has a ch)se relation ; 

 they differ, however, by more numerous divisions, and especially by tiieir dis- 

 position to slightly curve up in reaching the borders. By this character, the 

 species is allied to Fteris parschlugiana, Heer, Bornst. Fl., p. 7, j)!. 1, fig. 1, 

 which has the veins divided about in the same way. 



Lately, after the printing of the plate and the preparation of the descrip- 

 tion, I have received from Kev. A. Lakes, and found at Golden, a splendid 

 specimen, with one leaflet preserved in its integrity. It is seventeen centi- 

 meters long, three and a half centimeters broad below the middle, linear-oblong, 

 rapidly narrowed near the point to an acumen, sharply, nearly equally dentate 

 from a little above the base, which is unequilateral, rounded on one side, 

 cuneate on the other, broken near the'point of attachment, where it is narrowed 



