95 



o. 5 — 2 cm. long (4.5 — 5. o cm. long in forma longifoluis), normally arranged in closely imbricating 

 whorls or plates, the constituent flabellules being either laterally coherent into collars which 

 completely encircle the stipes, or into less complete collars or plates, or becoming completely 

 detached from one another. 



Filaments of flabellules 60 — 90 [j. in diameter above, 200 — 300 u. at base, six or more 

 times dichotomous, and laterally cohering in one plane, calcified, rigid, here and there constricted 

 along the internodes (rarely beaded). 



Filaments of stipes bearing lateral appendages 5 — 7 times dichotomously divided and 

 terminated by very narrow, more or less dactyline, obtuse or truncate apices. [Figs. 183 — 188]. 



forma typicus A. & E. S. Gepp 1. c. 



Hab. Atlantic. West Indies, Bahamas (figured by Ellis and Solander (loc. cit.) sub nom. Coral- 

 lina Phoenix). — Banc de Bahama, Herb. Lamouroux ! and Herb. Mus. Paris ! 



Flabellules about 15 mm. long, about 10 mm. wide, forming an ovoid capitulum (about 

 5 cm. long by 3 cm. wide), which for three-quarters of its length is penetrated by the stipes 

 (rhachis). [Fig. 183]. 



forma brevifolius A. & E. S. Gepp 1. c. 



Hab. ATLANTIC. Bahamas, Bemini Harbour, in 1 — 6 dm. of water at lovv tide, M. A. Hoiue, 

 n" 3239! — Guadeloupe, Mazé n° 24, fère s ér. in Herb. Mus. Brit.! 



Flabellules 5 — 10 mm. long, about as wide as long, usually laterally conjoined into 

 ascending, sheathing, densely imbricated collars or verticils arranged in a neat capitulum, which 

 is often cylindric or elongato-conical ; stipes (rhachis) percurrent almost to the apex of the 

 capitulum. Filaments of flabellules 90 to 70 u. in diam. above, up to 300 u. at the basal pedicel. 

 [Figs. 184—186]. 



forma longifolius A. & E. S. Gepp 1. c. 



Hab. ATLANTIC. Florida, Key West on sandy bottom in 6 dm. of water at low tide, Howe n° 1612! 



Flabellules 20 mm. or more long, 4 — 5 times longer than broad, cuneato-linear (elongate, 

 up to 50 mm. long and 6 — 8 mm. wide, in one abnormal specimen which has a stipes 15 cm. 

 long), truncate or obtuse and entire at apex or sometimes laciniate, usually ascending and 

 imbricate, in large plants not coherent into collars. Stipes (rhachis) penetrating to l / 3 — 3 / 4 of the 

 length of the capitulum (depending upon the length of the flabellules). Filaments of flabellules 

 mostly 60 p. (rarely 55 y.) in diam. above, increasing to 200 — -220 u. at the basal pedicel. 

 [Figs. 187, 188]. 



Rhipocephalus phoenix is characterised by the form of its capitulum. This consists of a 

 central rhachis from which arises normally a close series of ascending imbricating verticillate collars 

 or plates, each composed of one or more flabellules. Each flabellule emerges from the rhachis 

 as a short simple filament which, dividing dichotomously, first at short intervals (generally four 

 close to base), then at greater or vastly increased distances, but always in one and the same 



