526 CEEAMIACEAE. 



4. f. 26. Au 1917), is an exceedingly minute, almost microscopic plant tHat 

 creeps on rocks in caverns in company with other algae. It is monosiphonous 

 and uncorticated throughout. The creeping parts are attached by discs or 

 manifest rhizoids; the erect, ascending, or semiprostrate, flexuous main 

 branches are less than a line long, and have a more or less elongate naked stipe 

 above which they are regularly and oppositely pinnate or somewhat bipinnate, 

 the pinnae patent or somewhat divaricate, mostly 4-12 cells long, usually a 

 pair from the upper part of each internode. In the more or less bipinnate 

 conditions, the pinnules, 1-4 cells long, are chiefly confined to a secund row 

 along the upper (inner) side of the pinna. Occasionally a pinna will develop 

 more luxuriantly, like one of the main suberect branches. Cells of the 

 rhizome are mostly 1^-4 times as long as broad, those of the main suberect 

 axes li-2 times as long as broad. Tetrasporangia occur at the ends of the 

 pinnae and are tetrahedrally divided (tripartite). The nearest relative of this 

 species is perhaps the Irish cave-inhabiting Ptilothamnion lucifugum Cotton, 

 from which, however, it is amply distinct. The Bermuda plant was found 

 by F. ,S. Collins in a cave by the Ducking Stool. (Phyc. Bor.-Am. 2190, as 

 Gymnothamnion hipinnatum Collins & Hervey.) Apparently endemic. 



Spermothamnion gorgoneum (Mont.) Bornet, is a name that may be used 

 tentatively for a plant that forms a delicate red-purple plush on the surface of 

 species of Codium (Bethel's Island, Collins S488). The plant is monosiphonous 

 and uncorticated throughout, sending up erect somewhat flexuous branches less 

 than a line long from a creeping basal filament,, the erect branches simple or 

 rather sparingly laterally or subdichotomously ramified, the branchlets often 

 subsecund, very rarely opposite or 3-vertieillate. The cells are mostly 3-7 

 times as long as broad. The Bermuda specimen examined seems to be sterile, 

 as was also, apparently, the African type of the present species. The Ber- 

 muda plant is manifestly different from the cystocarpic and polysporic codiico- 

 lous plants from Jamaica ((Phyc. Bor.-Am. 441) and Barbados (Vickers, Alg. 

 Barb. 179) that have been distributed as SpermotJiamnion gorgoneum. 



Spermothamnion macromeres Collins & Hervey, forms soft cushions about 

 half an inch high on sand-covered rocks near the low-water mark, with Poly- 

 siphonias and other small algae, as at Pink Bay and Gravelly Bay (Phyc. Bor.- 

 Am. 2044). Like other members of the genus, the plant is monosiphonous and 

 uncorticated and sends up erect branches from a creeping base. The erect 

 branches are simple, sparingly subdichotomous, or provided with a few 

 lateral branchlets. The cells are mostly 4-10 (-15) times as long as broad, 

 often curved, and commonly contracted at the septa. The tripartite tetra- 

 sporangia are loosely clustered, sessile or pedicellate. Apparently endemic. 



Griffithsia globulifera Harv. {G. Bornetiana Farl.). The Griflathsias are 

 delicate, monosiphonous, uncorticated, cespitose plants, the filaments mostly 

 erect and regularly dichotomous, or, in some species laterally branched. The 

 tetrasporangia, in the Bermuda species, are borne on minute branchlets form- 

 ing whorls at the upper nodes. The cystocarps also occur at the nodes and 

 are furnished with an involucre. In G. glohulifera, the antheridia densely 



