64 UNITED STATES GEOLOGICAL SURVEY— TERTIAKY FLORA. 



liygodiuni conipactum, Lesqz. 



Plate V, Fig. 9. 



Lygodium compactum, Lesqx., Annual Report, 1869, p. 19G. 



Pinnnle or lobo linear-lanceolate, entire, slightly broader above the base ; lateral veins on a very 

 acute angle of divergence, all very close from the base, forking once or twice. 



This fragment is scarcely sufficient to indicate the generic relations. By 

 its close lateral veins it might be compared to Lygodium neuropteroides, de- 

 scribed above. But the veins in this species, though as close to each other, 

 are more straight and less divided. The borders are lacerated on the right 

 side of the leaflet toward the base, and thus it appears to represent a mere 

 lobe of a palmately divided pinnule. 



Habitat. — Marshal's Mine, Colorado {Dr. F. V. Hayden). 



RHIZOOARP^. 



This subclass is represented in a fossil state by Salvinia and Pinnularia 

 only. In the present flora, Salvinia has representatives in the boreal Asiatic 

 regions, and also in tropical America. Europe has one species only, S. natans, 

 which, according to Pursh, has been found also in a small lake of New York 

 State, but has not been seen until now by any other botanist. Five fossil 

 species have been described from the Miocene of Europe. 



SALVINIA, Mich. 

 Salvinia cyclopliy Ila, Lesqx. 



Plato V, Figs. 10, 10 o. 



Salvinia cyclophyUa, Lesqx., Annual Report, 1873, p. 408. 



Leaves nearly round, truncate or slightly cordate at the base, very entire ; middle nerve thin 

 lateral veins alternate, on a broad angle of divergence ; areolie polygonal. 



The leaf, finely preserved, is twenty-one millimetres long, twenty-five 

 millimetres broad, therefore slightly reniform, with a half-round, narrow 

 middle nerve and lateral veins very thin, scarcely thicker than the nervilles, 

 on an open and variable angle of divergence, some of them in right angle to 

 the midrib, and apparently running to the borders; the areolation is irregu- 

 larly quadrate, polygonal, comparatively small, distinct. 



By the form of its leaves, the species is related to Salvinia Reussii, Ett. 

 (Bil. Fl., p. 18, pi. ii, fig. 21), which, however, has a difl^crent areolation. 

 Our figure shows the secondary veins slightly more distinct than seen upon 

 the specimens, where they are scarcely distinguishable without a glass. 



Habitat. — Michlle Park, Colorado {Dr. F. V. Hayden). 



