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



more ; near the base of the tuft more slender, 150-200 ^ diam., 

 with thinner walls, not striate, with numerous short, patent 

 or recurved ramuli, scattered or secund. On stony beaches, 

 lower Ijtoral and upper sublitoral. Alaska. 



A coarse species, but not matted like most species of Spongo- 

 morpha ; it might be a question whether it belongs in this genus 

 or in Cladophora ; but the filaments usually larger at the tip, 

 never tapering, the cells short below, longer above, indicate the 

 present genus. Since the publication of Cladophora alaskana it 

 has been possible to examine authentic specimens of Ruprecht's 

 Conferva duriuscula, and there is no doubt of the identity ; 

 Ruprecht's description, however, is so scanty that no decision 

 was possible from it ; De Toni placing the species in Chaeto- 

 morpha. 



2. S. HYSTRIX Stromfelt, 1887, p. 54; Cladophora hystrix 

 P. B.-A., No. 982. Fronds rich green, in rather dense tufts, 

 filaments straight, very erect, except those at the base of the 

 tuft, which are somewhat more open ; about 100-300 /* diam. at 

 the base, 200-500 p. diam. at the tip ; cells up to 4 diam. long at 

 the tip, %-iyz diam. long below ; rhizoidal branches fairly com- 

 mon in the older parts, 40-70 /u, diam., cells 3-10 diam. long. 



Resembling 5". arcta, but stouter and with shorter cells ; a 

 distinctly arctic species, found on the Massachusetts coast only 

 in a reduced form, while 5*. arcta is practically the same in 

 Greenland as in Long Island Sound. Three forms are reported 

 from Greenland. . 



Forma typica (Jonsson) nov. comb. ; Acrosiphonia hystrix 

 forma typica Jonsson, 1903, p. 368. Fronds up to 15 cm. high, 

 filaments 300-500 p. diam., not much entangled. 



Forma littoralis (Jonsson) nov. comb. ; Acrosiphonia hystrix 

 forma littoralis Jonsson, 1903, p. 370. Tufts 4-10 cm. high, 

 filaments 200-300 /u diam., considerably entangled. 



Forma debilis (Rosenv.) nov. comb. ; Cladophora arcta forma 

 debilis Rosenvinge, 1893, p. 908. Tufts not over 10 cm. high, 

 with few long branches, but many short, subsimple, often 

 secund branches, of about equal length. 



3. S. LANOSA (Roth) Kiitzing, 1849, p. 420 ; Cladophora 

 lanosa Harvey, 1846-51, PI. VI; 1858, p. 76; Farlow, 1881, p. 

 51 ; P. B.-A., No. 661. Fronds fastigiate, erect, light green, 

 not over 5 cm. high, 30-40 //, diam., branches erect, usually 

 arising some distance below top of cell ; cells uninucleate, 2-6 



