400 KEY TO THE HIGHER ALGH OF THE ATLANTIC COAST. 
F. Frond cylindrical, septate within oe ee 2 Oe 
G. Frond pierced with large fona tah holes, e o + + + = Agarum da 
G. Frond not pierced with holes, . . én 0) 8 ce oe A 
H. Frond wen ching, Pee SS ee a 
H. Frond simple, ae eae Oe 
I. Frond = Se ati a „e » Pundan ae 
I. Frond bag-like, or worm- like, jot Sonstricted, hes ible k 
J. Dichotomous, with wide axils, ilophora. f 
J. Stem mostly excurrent with many ae EL à a g 
J. Frond tubular; branches opposite, tapering to each end, Striaria. h 
K. Frond Seltadtical, branching, L 
K. apa or minute parasites p ERSEN of densely tufted filaments 
at base, free above, . . ed - +H 
K. Frond niekol irregular, Ia athesiā. n 
i 
sew herds eoa ery, meets of E D unbranched 
ong, slender speci dart 
Y. Frond cylindrical; branches opposite. . re 
Y. prn reperta alternate, either with tufts of brit green 
i 
L. Axis atin us, lax; A Aiamaöti race Ma m 
M. Tufts on Fucus; 4 to 1 inch high, . Elachista. 0 
M. Forming minute brown patches on Give: whe See: mene? p 
N. Frond rigid; each joint of pwei T e F. oo o 
N. Frond soft; each joint of a single ce P 
O. Stems not obviously jointed; ea whorled, " Cladostephus. q 
O. Whole frond articulate ; sety branched, . . Sphacelaria. T 
P. Frond capillary, much branched, . Ectocarpus. 8 
P. Frond simple, with pT of small branchlets, ‘ win pee 
Q. Air vessels tipped with filiform points. . ~ we 
Q. Air vessels nearly or quite pointless i ey 
R. Leaves glandular; air vessels not longer than their z pedicels . : : 
R. Leaves nearly glandless; pedicels very s ? 2 
8.. Leaves narrow, repand or sub-entire. . . . +--+ +++" * go 
S. Leaves broader, sharply serrate. . ow le 5 : 
T. Frond compressed, repeatedly anato. E ee ee v ; 
U. Frond flat, with a midrib a a E e ‘oe. 6 . 
U. Frond compressed, withou idrib. ee. Bi: 
V. Air vessels usually present; coarse species more common than 1 
V. No air vessels; frond dertate, Pe Ne eee ne eee es : 
V. No air vessels; margins entire. oy we $ 8 
W. Receptacles obtuse; nort ae + ae 9 
W. Receptacles acute; river mouths, etc Pa hee . ‘ ? u 
Young stems villous; deep water; rare. ‘ : * ee “2 
13 
or subulate spines, T 
Z. Piti reseb or cleft only at sek: ole: Oe 
Z. Frond finally deeply cleft. in 
a. Stipe very long, hollow, largest midwais ‘tea water. Pe 
