37 
1. Morphological similarities may be. induced. by wholly dis- . 
tinct causes and may serve wholly different ends. 
2. The majority of species (both vegetable and animal) are 
stable. Temporary lability may be induced artificially or other- 
wise. All subsequent changes again tend toward the stable 
form. 
3. The form of the lichen-thallus indicates a special morpho- 
logical adaptation to favor the function of assimilation. 
4. The phylogenetic morphological characters of lichens are 
of great significance in the formation of a natural system as well 
as in the consideration of phylogenesis in general. 
5. The more recently acquired characters uf lichens are to be 
found in the thallus; the oldest in the apothecial structures. 
6. The entire lichen-structure has undergone considerable 
change since its phylogenetic history. 
New or Noteworthy American Grasses.—V. 
By Gro. V. NASH. 
Ersanraus Tracy n. sp. 
Culms stout, erect, 2-4 m. high, smooth and glabrous, the 
nodes upwardly barbed with deciduous silky hairs, about 1 cm. 
long; sheaths closely embracing the culm, shorter than the inter- 
nodes, smooth, glabrous, except at the apex, where they are pubes- 
cent with deciduous, long, silky, appressed hairs; ligule rounded, 
about 5 mm. long; leaves 5 dm. long or more, I.5—3 cm. broad, , _ 
narrowed toward the base, long-acuminate toward the apex, 
strongly scabrous on both surfaces, pilose on the upper side toward — 
€ base; panicle ‘oblong, 3-5 dm. long, 8-12 cm. wide, cream-_ 
white, dense, the main axis and branches pubescent with long ap- 
Pressed silky hairs, the branches usually in 2’s, much divided, : 
ascending or nearly erect, 15 cm. long or less; spikelets lanceo- _ 
late, 5~6 mm. long, about one-half again as long as the internodes, 
yellowish brown, usually marked with red, less than one-half the 
length of the involucral hairs; first and second scales firm-mem- — 
branous, the former a little the longer, both pubescent with silky 
hairs, twice the length of the scales, the first acuminate, faintly 
7-nerved at the base, 2-toothed and prominently 2-nerved at the 
apex, the two nerves scabrous, the second scale acute, the nerves 
ardly discernible; third and fourth scales hyaline, shorter than” 
_ the first and second ones, ciliate on the margins, the third acute 
