336 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



1. C. ALBIDA (Huds.) Kiitzing, 1843, p. 267 ; Harvey, 

 1846-51, PI. CCLXXV; 1858, p. 80; Farlow, 1881, p. 51; P. 

 B.-A., No. 1227. Fronds soft, dense, pale green, filaments 

 20-30 /J. diara., cells 4-5 diam. long, delicate ; branching irregu- 

 lar, ramuli long, patent, blunt. Southern New England, 

 Southern Cal. Europe. 



The soft, spongy consistency and very slender filaments suf- 

 ficiently distinguish the growing plant, and generally the dried 

 specimen. 



Var. REFRACTA (Wyatt) Thuret in Lejolis, 1863, p. 60; P. 

 B.-A., No. 720; C. refract* Harvey, 1846-51, PI. XXIV; 1858, 

 p. 79. Upper branches and ramuli recurved; otherwise like 

 the type. New Jersey to Maine. Etirope. 



In habit quite different from the type, but not in dimensions, 

 etc. It seems to be commoner than the type, and to extend 

 farther north on this coast. It shades into the type, and older 

 specimens are liable to be mistaken for slender forms of C. flexuosa; 

 in the growing plant the texture is sufficient for distinction, ex- 

 cept from C. flexuosa forma densa ; in this case the dimensions 

 of cells must be depended on, as also in distinguishing from 

 forms of.C. refracta. 



2. C. GLAUCESCENS (Griff.) Harvey, 1846-51, PI. CXCVI ; 

 1858, p. 77; Farlow, 1881, p. 52; P. B.-A., No. 817. Fronds 

 10-40 cm. long, glaucous or yellowish-green, loosely tufted, 

 much branched, ending in long, erect, acute, alternate or some- 

 times secund ramuli; cells at base 50-60 /u diam., in ramuli 

 25-30 /u. ; cells usually 4-6 diam. long, sometimes considerably 

 longer. Florida to Labrador. Europe. 



A plant of the litoral zone, and in the northern part of its 

 range, a plant of spring and early summer. It is common in 

 warm upper pools, exposed to the full sunshine, the upper part 

 of the tuft fading almost to white. It grows also in marsh pools 

 and shallow bays, where the water is warm. 



3. C. RUDOLPHIANA (Ag.) Harvey, 1846-51, PI. LXXXVI ; 

 1858, p. 80; Farlow, 1881, p. 54; P. B.-A., No. 267. Fronds 

 loose, soft, yellowish-green, gelatinous, up to a meter in length ; 

 main filaments 40-60 p. diam., branches alternate or opposite, 

 patent, flexuous, ramuli secund, tapering, about 20 p. diam., 

 cells always much longer than broad, sometimes up to 20 diam. 

 long. Kennebunk, Maine to New Jersey, and probably farther 

 south. Europe. 



