ON GENERA AND SPECIES. ` 39^ 
and age of individual plants of the same species. Further 
investigations, however, are required before the vascular 
_ structure of the stipes can be made of service as a distin- 
guishing character for either genera or species, and this 
can only be satisfactorily obtained by a series of observa- 
tions of living plants. 
M. Fée gives a systematic arrangement of his method of 
classification, which occupies nearly five double-columned 
pages; but the many divisions, sub-divisions, figures, 
letters, and arterisk, renders it necessary to be very care- 
fally studied before it can be well understood. The fol- 
lowing is sufficient to show M. Fée’s mode of classifying 
genera, from which it will be seen that plants most 
opposite in natural habit are associated, consequent on 
characters derived from the form and position of the sori, 
and in being naked or indusiate and the different forms of 
` Ge latter, and therefore cannot be considered otherwise than 
as an artificial arrangement of complicated construction. 
_ Abstract of Fée's arrangement :— 
Orper—POLY PODIACEA. 
I. CATHETOGYRATEÆ. 
 Aerosticheae, Gen. 19. (Hz. Acrostichum, Platycerium, 
~ Leptochilus.) 
 Lomarieae. Gen. 8. (Hz. Blechnum, Acropteris, Hymen- 
.  elepis.) ! 
 Vittarieae. Gen. 10. (Ez. Pteropsis, Drymoglossum, ` 
.. Lemogramma.) 
periclis Gen. 5. (Ez. Monogramma, Aën, 
el. Lindsayew. Gen. 5. (Ez. Isoloma, Schizoloma, 
