578 



CEEAMIACBAE. 



Family 12. CERAMIACEAB. 

 1. SPEEMOTHAMNION Aresch.; Fries, Summa Teg. Soana. 127. 1845. 



Cells of erect filaments mostly 10-20 « In diameter, 3-6 times as long as broad; 

 tetrasporangia on 1-4-celled pedicels ; plants usually grow- 

 ing on Qalaxaura. 1. s, investiena. 

 Cells of erect filaments mostly 20— 40« in diameter, 2-5 times 

 as long as broad. 

 Vtnaceous-purple or Indian lalce, on Codium, manifestly 



repent. 2, S. gorgoneum. 



Usually dark vinaceous-brown, under shelving rocks and on 



Jania, Oalaxaura, etc., intricate, less manifestly repent. 3. S. speluncarum. 

 Cells of erect filaments 40— 65« in diameter, S-l.^ times as long 

 as broad; terminal cells clavate, 26-40 « in diameter, walls 

 of all cells 6—14 a thick ; tetrasporangia terminal, often more 

 or less corymbose ; plants growing on rocks. 4. £f. macromeres. 



Cells of erect filaments 50-115 « in diameter, 3-7 times as long 

 as broad, their walls 5-40 u thick; terminal cells commonly 

 cylindric, often only 12-15 « in diameter, their walls 1-2 « 

 thick ; tetrasporangia at nodes, solitary or more commonly 

 several and unilaterally glomerate or subverticillate ; plants 

 on or with other algae. 5. S. gymnocarpum. 



1. Spermothamnion inv^stiens (Crouan) Vickers, Ann. Sci. Nat. Bot. IX. 1: 



64. 1905. 



Callithamnion investiens Crouan; Schramm & Maze, Alg. Guad. 7. 1865 

 [not seen]. 



On Oalaxaura fiagelliformis, G. sutverticillata, and G. comans, and on and with 

 Jania (growing on Sargassum) , Great Bahama, Watling's Island, Mariguana, and 

 Caicos Islands : — Bermuda to Barbados. Type from Guadeloupe. 



2. Spermothamnion gorgoneum (Mont.) Bornet; Vickers, Ann. Sci. Nat. Bot. 



VIII. 4: 305. 1897. 



Callithamnion gorgoneum Mont. Ann. Sci. Nat. Bot. IV. 8: 289. 1857. 



On Codium isthmocladitm. Berry Islands : — Bermuda to Barbados ; Canary Islands 

 and Cape Verde Islands. Type from island of St. Nicholas, Cape Verde Islands. 



3. Spermothamnion speluncarum (Collins & Hervey) M. A. Howe, comb. nov. 



BhodocTiorton speluncarum Collins & Hervey, Proc. Am. Acad. 53: 148. 

 1917. 



Variable in length of cells and thickness of the cell -walls ; cells mostly 2—4 

 times as long as broad, but occasionally as much as 8 times; cell-walls usually 

 3-6 ;U. thick, but ranging up to 12^ thick; tetrasporangia occurring mostly on 

 the lower part of the main erect filaments, solitary or rarely two (opposite) on a 

 segment, ellipsoid or subglobose, 52-65 /i in maximnm diameter, subseound, 

 sessile or on 1- or 2-celled pedicels; antheridial stands terminal, short-eylindric 

 or ovoid-ellipsoid, about iO in X 20-28 ft. Erect filaments sometimes tortuous 

 and intricate, forming intertangled cushions. Belated to the North-European 

 S. roseolum (Ag.) Pringsh., especially to the form occasional in herbaria under 

 the name Callithamnion repens Lyngb., but filaments more intricate and flexuous, 

 more slender (commonly 22-39 /i vs. 36-56 /i), cells shorter (usually 2-4 times 

 vs. 3-8 times as long as broad), more often dolioform, and more often coUabent. 



Under shelving rocks and on various algae (Chainaedoris, Oalaxaura, Jania. etc.) 

 and on sponges, in shaded situations, near low-water mark. Rose Island, Great Ba- 

 hama, North Cat Cay, Mariguana, and Great Ragged Island : — Bermuda. Type (ster- 

 ile) from Bermuda. 



4. Spermothamnion macromferes Collins & Hervey, Proc. Am. Acad. 53: 132. 



1907. 



On surf -beaten, sand-covered rocks at low-water mark, Berry Islands : — Bermuda. 

 Type from Bermuda. 



