THE ALGAE OF BERMUDA. 89 



2. Frond dichotomously branched, with or without lateral proliferations. 



3. 



3. Frond usually rather broad, very regularly dichotomous, axils usually 



wide, tips rounded, proliferations on old plants only. 1. D. dichotorna. 



3. Not with above combination. 4. 



4. Frond very narrow, almost filiform throughout. 5. 



4. Frond of varying width, not appearing filiform throughout. 6. 



5. Regularly dichotomous, few or no proliferations except in very old plants. 



2. D. linearis. 



5. Dichotomous in younger parts, elsewhere with many proliferations, often 

 much entangled. 6. D. divaricata. 



6. Fronds narrow, dichotomous, few or no proliferations. 7. 



6. Fronds broad or narrow, divisions of dichotomies often unequal, some- 

 times appearing subpinnate, proliferations frequent. 



5. D. Bartayresii. 



7. Dichotomies distant, regular, divisions equal. 3. D. indica. 



7. Dichotomies close, some divisions long, some short, patent, acute. 



4. D. cervicornis. 



1. D. DICHOTOMA (Huds.) Lamouroux, 1809, p. 331; Harvey, 

 1846-51, PI. GUI; P. B.-A., No. 2175; Uha dichotoma Hudson, 1798, 

 p. 476. Rein; Hamilton, Kemp; up to 31 fathom depth, Moseley; 

 Tucker, No. 11; Cave near Ducking Stool, Farlow; Faxon; Build- 

 ings Bay, Inlet, Dec., Hervey. This species, the common one of 

 Europe and the most widely distributed of the genus, seems to be 

 rather uncommon in Bermuda; we have found it of only moderate 

 size, not at all like the large plants from North Carolina distributed 

 as P. B.-A., No. CXX. Antheridia have once been observed, but 

 no other form of fruit. There is little indication of rhizoidal filaments 

 in the Bermuda plants. 



2. D. LINEARIS (Ag.) Greville, 1830, p. XLIII; Kutzing, 1859, p. 

 9, PL XXI, fig. II; P. B.-A., No. 2031; Zonaria linearis Agardh, 

 1820, p. 134. Jew's Bay, July, Collins. In loose floating masses, 

 antheridia fairly frequent, no other fruit observed. The frond is 

 very narrow, seldom over 1 mm.; the forkings are rather distant, 

 axils narrow. The lower part of the frond was old and dry, but 

 showed no proliferations; no rhizoidal filaments were seen. 



3. D. INDICA Sonder in Kiitzing, 1859, p. 8, PL XVII, fig. 1; 

 Vickers, 1905, p. 59; 1908, part 2, PL XVIII; P. B.-A., No. 2030. 

 Kemp, as D. fasciola, in part; Ely's Harbor, Aug., Collins. Our 

 plants agree with the narrower form distributed by Miss Vickers under 

 No. 78; the width of the frond from 1-2 mm. remaining practically 

 the same throughout in each individual. The divisions are quite 



