CHAETANGIACEAE. 557 



45-125 ,u in diameter, readily visible, commonly reduced to three or four rather 

 easily separable filaments towards apex, the cells subcylindric or fusiform, 

 mostly 52-300 /i X 11 75 .w., descending rhizoids 3-8 fj, in diameter few in 

 younger parts; fascicles of assimilatory filaments mostly 150-300 /j. long, 3 or 

 4 times dichotomous, intermingled in older parts with simple or subshnple fila- 

 ments 8-15 cells long, all beautifully moniliate or submoniliate in distal parts 

 at least, the distal or subdistal cells subglobose or bitruncate-subglobose to 

 ellipsoid or obovoid, 13-24 /j. long, 13-19 /u broad ; apical hairs very numerous, 

 becoming 300-800 ^ long, cylindrie-capitate, gelatinizing and leaving incon- 

 spicuous vestigia; dioicous; antheridia forming rather compact subglobose or 

 subhemispheric tufts 25-50 ft broad, crowning ultimate and penultimate seg- 

 ments; carpogonial branch slightly curved, 15-28^ broad, of four cells (often 

 with conspicuous intercellular spaces), situated latero-terminally on the second 

 or third (rarely first or fourth) segment of the fascicle; cystocarp compact, 

 subhemispheric or subglobose, 100-200 n broad, with a few rather inconspicuous 

 ascending involucral filaments; carpospores obovoid to pyriform-clavate, 25- 

 32 /j. X 14-18 n. 



On more or less exposed rocks, at or near the low-water mark (also found 

 washed ashore). Little Inagua (Howe 5?'i7 type), Rose Island, Whale Cay, Great 

 Stirrup Cay, Great Bahama : Florida (Key West, Mrs. G. A. Hall, Mrs. F. A. Cur- 

 tiss) ; Barbados (Tickers, Alg. Barb. 106 a coarse form). Liagora mucosa resembles 

 L. pedicellata so much in general habit that a microscopic examination is commonly 

 necessary for their distinction, yet it differs constantly in being dioicous, in the larger 

 tufts of antheridia, in the less distal and more lateral insertion of the more curved 

 carpogonial branch, and in the presence of a proper, even though rather inconspicu- 

 ous, ascending involucre for the cystocarp. It differs less constantly in the shorter, 

 more moniliform assimilatory filaments and in the more axial, less extra-peripheral 

 calcification. 



From Liagora piunata Harv., the species differs in being dioicous, in being less 

 calcified, in its greater mucosity, in its shorter, more moniliform assimilative fila- 

 ments, etc. 



From Liagora mcgagi/na Borg., recently described from St. Croix, L. mucosa, dif- 

 fers in being much more flaccid and mucous, in being less calcified, in the long and 

 numerous apical hairs, in the fascicles of the more moniliate assimilatory filaments 

 being about one half as long, in the absence of rhizoidal trichomes on the assimilatory 

 filaments (except for the decurrent rhizoid springing from the basal segment), in the 

 more curved, usually less stout, and more proximally situated carpogonial branches, etc. 



Family 3. CHAETANGIACEAE. 



1. GALAXAURA Lamour. Nouv. Bull. Sci. Soc. Phil. 3: 185. 1812. 

 DICHOTOMARIA Lamarck, Hist. Nat. Anim. sans Vert. 2: 143. 1816. 

 BRACHYCLADIA Sender, Linnaea 26: 514. 1853. 

 ZANARDINIA J. Ag. Sp. Alg. 3: 533. 1876. 



Thallus terete, villous, hirtous. or pubescent throughout with numerous, crowded 

 mostly free assimilatory filaments. Only tetrasporangia known for reproductive 

 organs ; so-called species of this group probably only non-sexual phases of other 

 species of very different habit. 



Long and short assimilatory filaments in obvious alternat- 

 ing transverse zones. 1. O. subvert icillata. 

 Long and short assimilatory filaments intermingled, not ob- 

 viously zonate. 



Thallus coarse, reddish, central axes mostly 12 mm. in 



diameter ; intervals between dichotomies mostly 1-3 



cm. : assimilatory filaments often branched, their basal 



cells commonly amyliferous. 2. G. comans. 



Thallus more slender, fuscous or reddish, axes mostly 



0.6-1 mm. in diameter. 



Thallus rather divaricately dichotomous, usually fus- 

 cous ; intervals between dichotomies mostly less 

 than 1 cm. : long assimilatory filaments mostly 



0.6-1.5 mm. long. 3. G. lapidcsccns. 



Thallus rather fastigiately dichotomous, usually red- 

 dish ; intervals between dichotomies commonly 

 more than 1 cm. ; long assimilatory filaments 

 mostly 0.150.7 mm. long. 4. G. flagclliformis. 



