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



cylindrical, 4-6 diam. long ; shorter in the branches, with con- 

 stricted joints; in the ramuli ellipsoid, 1-2 diam. long. Ber- 

 muda. Mcditerra n ea n . 

 No authentic specimens have been accessible, but the Ber- 

 muda plant agrees so well with Kiitzing's figure that the iden- 

 tity seems fairly well assured. 



19. C. CRYSTALLINA (Roth) Kiitzing, 1845, p. 213; 1854, 

 PL XIX, fig. 2. Fronds yellowish or whitish-green, soft, 

 glossy, 10-30 cm. high ; filaments slightly matted, distantly di- 

 trichotomously branched; main branches 80-140 p- diam., taper- 

 ing to 25-40 /A in the ramuli ; branching erect or patent ; upper 

 ramuli sometimes whorled or alternately secund ; cells cylindri- 

 cal, 4-12 diain. long. Mass., W. I. Europe. 



A quite variable plant, but usually marked by its light color 

 and silky gloss, which latter has given the specific names crys- 

 tallina, sericca and nitidissima to various forms. The long 

 cells, often as long in the ramuli as in the main filaments, are 

 also characteristic. The plant distributed under this name as 

 P. B.-A., No. 723, is probably not correctly determined. C. 

 sericca Vickers, 1908, p. 18, PI. XIV, may be a shorter jointed 

 and divaricately branched form of this species, but has also con- 

 siderable resemblance to the following. 



20. C. DALMATICA Kiitzing, 1343, p. 268; Vickers, 1908, 

 p. 19, PI. XIV.B. Fronds up to 5 cm. high, light green ; main 

 filaments 80-120 /n diam., simple or distantly dichotomous below, 

 trichotomous above, with many alternate or secund branches ; 

 cells 3-6 diam. long ; ultimate ramuli corymbose, incurved, 

 secund, 30-50 p. diam.; cells 1^-3 diam. long, nodes contracted, 

 membrane thickish. Barbados. f-'.uropc. 



21. C. GRACILIS (Griff.) Kiitzing, 1845, p. 215; Harvey, 

 1846-51, PL XVIII; 1858, p. 80; Farlow, 1881, p. 55 ; P. B.-A., 

 Nos. 1528, 1529, not No. 724. Fronds usually not over 30 cm. 

 long, yellowish or glaucous green, somewhat harsh to the 

 touch; main filaments up to 160 yu, diam., irregularly bent, 

 branching at the angles ; the branches more slender, set at the 

 tips with secund series of long, attenuate, acute ramuli, 40-60 /u, 

 diam. ; cells 3-5 diam. long throughout. Greenland to Key 

 West. Europe. 



A variable species, passing into C. lactcvirens, C. hirta, and 

 C. flexuosa ; see under the last for special distinctions. It 

 assumes various forms under different environment and at dif- 

 ferent stages of growth, and until one is familiar with it, will 



