136 DESCRIPTION OF SPECIES. 



HYPNUM, Linn. 



II. \ piiiini Haydenii, Lesqx. 

 "U. S. Geol. Rep.," vii, p. 44, p!. v, figs. 14-146. 



RHIZOCARPE^E. 



SALVINIA, Mich. 

 Salvinia cyclophylla, Lesqx. 

 "U. S. Geol. Rep.,'' vii, p. 64, pi. v, figs. 10,10a. 



Salvinia Alleni, Lesqx. 

 Plate XXI, Figs. 10, 11. 

 "U. S. Geol. Rep.," vii, p. 65, pi. v, fig. 11. 



The species is common and has been obtained in large well-preserved 

 specimens by the different collectors. The leaves are merely variable in 

 size, obtuse or slightly emarginate at the apex, topped by the point of the 

 excurrent nerve. 



EQUISETACEjE. 



EQUISETUM, Linn. 

 Equisetum Wyomingense, Lesqx. 

 "U. S. Geol. Rep.," vii, p. 69, pi. vi, figs. 8-11. 



Equisetum Haytlenii, Lesqx. 

 "U. S. Geol. Rep.," vii, p. 67, pi. vi, figs. 2-4. 



ISOETEjE. 



ISOETES ?, Web. 



Isoetes brevifolius, sp. nov. 



Tufts small, compact; leaves cylindrical, acuminate, coming out of a small cylin- 

 drical stem or rhizoma. 



The leaves are 1 to 2 millimeters in diameter, 4 to 6 centimeters long, 

 narrowed to a point, apparently smooth. The small tufts much resemble 

 Isoetes Brawnii, Heer, as figured in "Fl. Tert. Helv.," pi. xiv, fig. 5, the 

 leaves being only shorter and narrower. 



Hab. — Florissant. Specimen No. 66. of the collection of Mr. R. D. 

 Lacoe, of Pittston, Penna. 



