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



In dimensions and general form somewhat like coarse C. 

 gradlis of the northern type, but distinguished by ramuli gen- 

 erally distributed over the filaments, not merely at the tips. 

 The amount of ramification varies much ; the most characteris- 

 tic forms have long, little branched filaments set with longer 

 or shorter secund series of ramuli ; the much branched forms 

 are less characteristic, and require more careful examination. 



23. C. REFRACTA (Roth) Areschoug, Alg. Exsicc. Scand., 

 No. 338; Farlow, 1881, p. 52; P. B.-A., No. 573. Fronds 

 tufted, glaucous or dull green, 10-20 cm. high ; filaments rather 

 stiff, 100-120 /u. diam. below, 40-50 /u, in the ramuli; cells 2-3 

 diam. long ; branches of all orders at first erect, then reflexed ; 

 ramuli often secund, blunt. N. S. to N. J. Europe. 



The regularly reflexed branches of all orders distinguish this 

 from all our other species of the same range except some forms 

 of C. ftexuosa and C. albida var. refracta ; the former is a more 

 open plant, with flexuous rather than refracted branches ; the 

 latter has more slender filaments and softer substance. C. re- 

 fracta has a characteristic habit, hard to describe, but fairly rec- 

 ognizable when once seen. For C. refracta Harvey, see C. 

 albida var. refracta. 



24. C. BERTOLONII var. HAMOSA (Kiitz.) Ardissone, 1886, 

 p. 242 ; C. hamosa Kiitz., 1854, PI. VIII, fig. 2. Tufts 3-iocm. 

 high, dark green; filaments rather stiff, 80-100 p. diam. in the 

 main divisions, 25-30 p. in the ramuli ; much branched, main 

 divisions di-trichotomous, set with alternate, opposite or whorled 

 branches, usually short, and with densely set, secund, recurved 

 ramuli; cells 1^-3 diam. long, rarely more; terminal cells 

 rounded, not tapering. Cal. Mediterranean. 



The California plant seems to be more slender than the 

 European, seldom exceeding 60 /j. in the main branches and 

 25 p. in the ramuli. The dark color, short cylindrical cells and 

 elegant feathery tips, with a long series of secund, usually 

 slightly recurved ramuli on the similarly recurved branch, are 

 fairly clear characters. 



25. C. MICROCLADIOIDES Collins, 1909, p. 17, PI. LXXVIII, 

 figs. 2 and 3. Fronds more or less densely tufted, 10-20 cm. high ; 

 filaments about 200 /A diam. at base, cells 4-6 diam. long ; stiff, 

 straight or flexuous, distantly di-trichotomous, branches simi- 

 lar, erect or more or less recurved, bearing on the upper (inner) 

 side numerous short branches, rarely with very short branches 



