Perna | 
Canadian meets the Alleghanian flora along the upper slopes, and 
hhow far the latter extends down the mountain sides; 3.—the alti- 
tude to which the Carofinian rises to meet the Aleghanian ; 4.— 
the line where the Louisianian and the Carolinian come together. 
This can be done only by the collection and tabulation of an im- 
Mense number of altitudinal observations on all the plants of 
Eastern North America, and I take occasion through this channel 
to ask my fellow botanists to note and record careful observations 
when in the field, and report to me at their convenience. 
Of course, the areas, belts or lines, as the case may be, will be 
affected by local conditions, and are influenced in the same way 
by the latitude as well as the altitude, the latter being a more or 
less perfect exhibition of the former in a perpendicular manner. 
On account of the influence of latitude the lines which bound the 
different areas will, if we start at the north and go south, gradually 
converge towards the mountains and rise towards the summits as 
the latitude decreases. If the direction be from south to north 
the lines will descend from the highlands and diverge at angles or 
curves from the mountains, expanding into broad areas towards 
the north. The problem is, as already stated, to locate these lines. 
With the assistance of data at hand and the geographic dis- 
tribution, the ferns as given below have been placed each in its 
respective flora or floras, and by the aid of altitudes the direction 
of the lines can be seen in a general way. - 
Potypopium potypopioipEs (L.) A. S. Hitchcock. (Polypodium 
incanum, Swartz.). Ranges from sea-level, from Virginia Beach, 
Va. (Britton) to Florida and the Gulf coast to 4,000 feet on 
Blowing Rock Mt., N. C. (Small & Heller); occurs at 1,000 
feet in Winston county, Ala. (Mohr); at 3,000 feet at Estatoah 
Falls, Ga. (Small); at 2,100 feet at Marion, Va. (Miss Vail). 
[| Southern Carolinian ; Louisianian.| 
PoLypopiuM VULGARE L. Ranges from sea-level along the At- 
lantic coast, from Central New Jersey northward to 5,800 feet 
on Grandfather Mt., N. C. (Small & Heller); occurs at 1,000 
feet in Winston county, Ala. (Mohr); at 3,000 feet in Rabun 
county, Ga. (Small); at 5,678 feet on White Top Mt., Va. 
(Small); at 2,700 feet in Garrett county, Md. (J. D. Smith); at 
