though passingly alike, are not in reality closely allied. Rhipocephalüs is more nearly allied 

 with the simple species of Udotea, namely U. javensis and U. glaucescens, being as it wei 

 a stalked community of those species ; in the same way as Penicillus is a stalked community 

 of Espera (see pp. 72, 89). Rhipocephalüs and Penicillus clo however find an intermediate in the 

 curieus dimorphic Tydemania expeditionis, which produces flabellules near its base and glomeruli 

 above, composed of iïlaments dichotomously branched in alternating planes (see p. 66). 



Rhipocephalüs Kützing 

 Phyc. Gen. 1843. p. 311. 



Nesaea et Nesea auctorum pro parte. 

 Penicillus auctorum pro parte. 



Rhipocephalüs J. G. Agardh Till Alg. Syst. V. 1887. p. 64. 

 Rhipocephalüs De Toni Syll. Alg. I. 1889. p. 503. 



Rhipocephalüs Collins Green Alg. N. Amer. in Tufts College Studies II. 1909. p. 393. 

 Rhipocephalüs Wille in Engler und Prantl natürl. Pflanzenfam. I. Teil, 2. Abteil. 1S90. p. 142; 

 also Nachtrage 19 10. p. 129. 



Root-mass fibrous, long, branched, sometimes matted into a dense bulb. 

 'Stipes erect, terete, encrusted externally, hollow or laxly fibrous within, composed of 

 numerous, longitudinal, interwoven filaments, dichotomously branched, and bearing dichoto- 

 mously branched lateral appendages, the obtuse or truncate peripheral endings of which are 

 approximated together to form a cortex, which becomes thickly calcified, and appears very 

 minutely porose under the microscope. 



Capitulum green to glaucous or bleached, globose or oblong to cylindrico-conic, com- 

 posed of numerous normally clistinct and imbricate, erect or ascending (rarely spreading), flat, 

 cuneate flabellules, often arranged in pseudo-verticils ; each flabellule emerging from the rhachis 

 as a single filament which divides dichotomously 4 — 6 or even more times in one plane. 



Filaments of the flabellule parallel, contiguous and cemented together, or approximated 

 and free, constricted at the base of each branch, covered with a porose calcareous pellicle. 



Key to the Species. 



Filaments of flabellules laterally coherent throughout their length, 60 — 90 p. 



above in diameter, 200 — 300 u. at base 1. R. phoenix. 



Filaments of flabellules free throughout their length, 160 — 200a above in dia- 

 meter, 200 — 350 ix at base; stipes usually twice as long as in R. phoenix. 2. R. oblongns. 



1 . Rhipocephalüs phoenix Kützing 



Phycologia generalis 1843. p. 311. 



Corallina Phoenix Ellis et Solander Nat. Hist. Zooph. 1786. p. 126. tab. 25, figs. 2, 3. 



Corallina Phoenix Gmelin Linn. Syst. Nat. vol. I, part VI. 1790. p. 3843. 



Corallina Phoenix Bosc Hist. Nat. des Vers (Suites a Buftbn) vol. III. i8m° Paris (Déterville) 



1802. p. 72. 

 Nesma Phoenix Lamouroux Mém. Class. Polyp. Corall. in Nouv. Buil. Sci. Soc. Philomat. 



Paris III. 1812. p. 185. 



