582 



CEEAMIACEAE. 



11. CERAMIUM Ag. Syn. Alg. Scand xxvi. IS 17. 



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

 ? EPISPERMA Eaf. Free. Soraiol. 48. 1814. 

 BORYXA Grateloup. Bory, Diet. Class. Hist. Nat. 2: 412. 



Filaments continuously corticated. 



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. 



Segments mostly shorter than broad or subequal, becom- 

 ing 2-8 times longer than broad below ; tetrasporangia 

 often cruciate or decussately paired. 



.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. 

 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. 



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. 



1822. 

 C. nitt'ns. 



C. tenuissimum. 

 C. cruciatiim. 



4. C. subtile. 



5. C. byssoideum. 



6. C. corniculatum. 



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



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



? Ceramium leptophloemn 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, Exurua 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 diaplianum 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 Digenca, 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 Rhizopliora, 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. 



