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



fig. 3. Flabella 20 ram. long and more, irregular, deeply and 

 irregularly laciniate, ascending or divergent, forming a bristly 

 head. Fla. 



5. UDOTEA L,amouroux, 1813, p. 27. 



Frond arising from a mass of rhizoids ; stipe erect, with dis- 

 tinct cortex, terminating in a flabelliform, more or less distinctly 

 zonate lamina, consisting of continuous, branching filaments 

 with more or less numerous short branches, attached to each 

 other by short processes, and sometimes developing laterally in- 

 to a more or less definite cortex ; calcification more or less com- 

 plete ; reproduction unknown. 



Distinguished from Avrainvillea by the corticated stipe ; from 

 Cladocephalus by the cortex of the lamina, when present, not be- 

 ing formed of densely packed, labyrinthine branches as in the 

 latter. 



The evolution of all the forms of the subfamily Udotoideae 

 from a branching filament like Dichotomo siphon is best shown in 

 this genus. In the Mediterranean species U. minima Ernst the 

 filaments are loosely united or often quite free ; from this to 

 U. Flabellum, with no external indication of the original fila- 

 mentous structure, the intermediate stages can be seen in the 

 different species. See Ernst, 1904, for a clear statement of the 

 matter. 



KEY TO THE SPECIES OF UDOTEA. 



i. Whole flabellum with a stony coating. 2. 



r. No general stony coating. 3. 



2. Branches forming the cortex of the lamina capitate. 



6. U. argentea. 



2. Cortical filaments not capitate. 5. U. Flabellum. 



3. Little or no calcification. i. U. tomentosa. 



3. Individual filaments of the flabellum calcified. 4. 



4. Flabellum with a cortex of spinulose branches. 



4. U. spimilosa. 



4. Flabellum uncorticated. 5. 



5. Flabellum plane. 2. U. conglutinata. 



5. Flabellum concavo-convex to cyathiform. 3. U. cyathiformis. 



i. U. TOMENTOSA (Kiitz.) Murray, 1889, p. 239; Howe, 

 1907, p. 512. Fronds to 7 cm. high, bright green, uncalcified ; 

 stipe terete or flattened, 2-4 mm. wide, simple ; flabellum cunei- 

 form to obdeltoid, 3-5 cin. long, 1-3 cm. wide, entire or lobed, 

 little or not at all zonate, rather thick, spongy, with tomentose 



