582 



CEEAMIACEAE. 



11. CEBAMIUM Ag. Syn. Alg. Scand xxvi. 1817. 



? APONA Adans. Fam. PI. 2: 2, 519. 1763. 

 ?EPISPERMA Eaf. Free. Somiol. 48. 1814. 

 BORYNA Grateloup. Bory, Diet. Class. Hist. Nat. 2: 412. 1822. 



Filaments continuously corticated. 1. c. nitens. 



Filaments manifestly zonate, corticated at nodes only. 



Filaments regularly and equally dichotomous, more or less 



fastigiate, apices forcipate. 



Segments mostly longer than broad, becoming 3-7 times 

 longer than broad below ; tetrasporangia triangularly 



divided. 2. C. tenuissimum. 



Segments mostly shorter than broad or subequal, becom- 

 ing 2-3 times longer than broad below ; tetrasporangia 

 often cruciate or decussately paired. 3. C. cruciatum. 



Filaments unequally dichotomous or showing various inter- 

 mediate conditions between dichotomy and lateral 

 branching. 



Upper margins of cortex-zones commonly showing in 

 younger parts verticils of delicate caducous mostly 

 1- or 2-celled hairs ; branching dichotomo-alternate 

 and slightly zig-zag. 4. C. subtile. 



Hairs wanting or very rare. 



Main filaments mostly 45 75 # in diameter; nodal 

 bands protuberant, bitruncate, most of the corti- 

 cating cells, or at least the lower with their longer 

 axes running transversely to the filament ; tetra- 

 sporangia on main filaments. 5. C. ~byssoideum. 

 Main filaments mostly 90-200 ^ in diameter; nodal 

 bands not protuberant, the corticating cells with 

 their longer axes lengthwise of the filament ; tetra- 

 sporangia on clavate or fusiform lateral branches. 6. C. corniculatum. 



1. Ceramium nitens (Ag.) J. Ag. Sp. Alg. 2: 130. 1851. 



Ceramium rubrum nitens Ag. Syst. Alg. 136. 1824. 



? Ceramium leptophloeum Kiitz. Linnaea 15: 740. 1841. 



Ceramium divaricatum Kiitz. Tab. Phyc. 13: 5. pi. 12. f. c-e. 1863. 



Rather common in shallow water, New Providence, Berry Islands, Joulter's Cay, 

 Great Bahama, Bimini, Exuma Chain, and Watling's Island : Bermuda and Florida 

 to the American Virgin Islands. Type from the " Antilles." 



2. Ceramium tenuissimum J. Ag. Sp. Alg. 2: 120. 1851. 



? Ceramium diapJianum tenuissimum Both, Cat. Bot. 3: 156. 1806. 



The usually sterile Bahamian plants referred tentatively to C. tenuissimum 

 seem, to agree essentially with other West Indian specimens currently thus re- 

 ferred, but their identity with the European type is doubtful. They are more 

 regularly dichotomous, more fastigiate, firmer and more rose-colored than the 

 plants here referred to C. subtile. 



On various other algae, roots of Rhizophora, etc., in shallow water, Great Ba- 

 hama, Exuma Chain, Mariguana, and Great Ragged Island : Europe ; Massachusetts ; 

 Bermuda ; and the West Indies generally. Type locality unknown. 



3. Ceramium cruciatum Collins & Hervey, Proc. Am. Acad. 53 : 144. pi. 4. f. 27, 



28. 1917. 



Similar in structure to the Bermudian plant, but less obviously repent and 

 taller, reaching a height of 1-3 cm. 



On Digenea, Thalassia, etc., and on rocks, near the low-water mark, Mariguana, 

 Caicos Islands, and Great Ragged Island : Bermuda. Type from Bermuda. 



4. Ceramium subtile J. Ag. Sp. Alg. 2: 120. 1851. 



On Chondria and various other algae, roots of Rhizophora, etc., in shallow water, 

 New Providence, Berry Islands, Great Bahama, Bimini, Joulter's Cay, Exuma Chain, 

 and Watling's Island : Mexico. Type from Vera Cruz. 



