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



flabellata Lamouroux, 1816, p. 311, PI. XII, fig. i ; Harvey, 

 1858, p. 26; P. B.-A., No. 272. Frond up to 15 cm. high, 

 stipe short, often indistinct ; flabellum entire and curieate-reni- 

 form or divided into a few similar lobes ; longitudinal filaments 

 of the flabellum flexuous, rather distant, their short ramuli 

 forming a cortical layer, the whole covered with a stony in- 

 crustation. Fla., W. I. 



Not to be mistaken for any other of our species, none of 

 which have the general stony coating. 



6. U. ARGENTEA Zanardini, 1858, p. 290, PI. XII, fig. i ; 

 Howe, 190?), p. 99 ; Gepp, 1909^.386. Calcified; stipe short ; 

 frond thin, subreniformly flabellate, longitudinally striate, only 

 slightly zonate, repeatedly proliferous ; lateral branches of main 

 filaments abundant, each terminating in a capitate or ungulate 

 head. W . I . Red Sea , In dia n Ocea n . 



Among our better known species U. Flabcllum is nearest to 

 U. argentea, but the latter has a shorter stipe, is of thinner text- 

 ure with more manifest radiate markings, along which it appears 

 sometimes to divide ; as it is plentifully proliferous from the 

 margin, a single plant may develop into an apparent colony. 

 Structurally it is distinguished by the capitate form of the 

 branches composing the cortex. 



6. CLADOCEPHALUS Howe, 19053, p. 569. 

 Not calcified ; frond arising from a mass of rhizoids ; stipe 

 erect, with central layer of parallel, dichotomous filaments, and 

 distinct cortical layer of much narrower, intricate, divaricately 

 dichotomous branches ; surmounted by either a distinct flabellum 

 or a brush-like head. 



The species with brush-like head resemble Pcnicillus, but are 

 uncalcified ; the flabellate species have the habit of Udotcct, but 

 are distinguished by the more definite cortex of characteristic 

 structure, as well as by the lack of calcification. 



KEY TO THE SPECIES OF CLADOCEPHALUS. 



i. With brush-like head. i. C. scoparius. 



i. With flabellum. 2. C. luteo-fnscus. 



i. C. SCOPARIUS Howe, 19053, p. 569, PL XXV, XXVI, 

 figs. 11-20; P. B.-A., No. 1334. Stipe 2-10 cm. high, 5-7 mm. 

 thick, cylindrical or somewhat complanate, often alate or can- 

 aliculate above, sometimes forked; head 3-8 cm. long, brush- 

 like, in shape from linear or fusiform to obovoid, more or less 

 flattened ; branches subcylindrical or complanate, up to 2 mm. 



