580 CEEAMIACEAE. 



beaten roeks between the tide-lines and as epiphytes on other algae, habitats 

 that are not characteristic of the northern G. globulifera. 



Joulter's Cay, Bxuma Chain, Atwood Cay, Calcos Islands, and Great Ragged 

 Island : — Massactiusetts to the American Virgin Islands and Barbados ( ?) . Type 

 from New York. 



2. Grifflthsia tenuis Ag. Sp. Alg. 2: 131. 1828. 



Callithamnion tenue Harv. Ner. Bor.-Am. 3: 130. 1858. 

 Grifflthsia thyrsigera (Thwait.) G-run. Alg. Fidschi 8. 1877. 



An antheridial fragment, washed ashore, Berry Islands :-^Massachusetts and 

 Bermuda to Barbados ; Adriatic Sea ; Ceylon ; Australia ; etc. Type from Venice. 



4. CALLITHAJVLNTON Lyngb. Hydroph. Dan. 123. 1819. 

 1. Callitliamnion Halliae CoUins, in C, H., & S., Phyc. Bor.-Am. 698. 1900. 



Belated to C. corymbosum and C. byssoides, but differs from both in having 

 the main axes uncorticated throughout. 



On other algae at low-water mark, under shelving rocks (and washed ashore), 

 Great Bahama and Bxuma Chain : — Florida. Type from Key West, Florida. 



5. SEIROSPOEA Harv. Phyo. Brit. pi. Zl. 1846. 

 1. ? Seirospora occidentalis Borg. Bot. Tidsskr. 30 : 14. /. 8, 9. 1909. 



The scanty fertile material has the triangularly divided tetrasporangia sessile 

 or on one-celled pedicels; paraspores 30-40 « broad, in branching, subterminal tufts; 

 main axes uncorticated throughout. Exuma Chain : — American Virgin Islands. Type 

 from sound between St. Thomas and St. Jan. 



6. HAIiOPI^EGMA Mont. Ann. Sci. Nat. Bot. II. 18: 258. 1842. 

 Ehodoplexia Harv. in Hook. Ic. PL 7: pi. 613. 1844. 

 1. Haloplegma Duperreyi spinulosum M. A. Howe, subsp. nov. 



Differs from typical H. Duperreyi 'Mont, in having a thallus that is beset 

 with numerous rigid subspinescent ramelli usually in twos or threes and 25^140 fi, 

 (2-11 cells) long, the cells of these ramelli mostly 1.5-3 times as long as broad. 



Between the tide-lines on a rock shelf, under an overhang. Cave Cays, Exuma 

 Chain (Howe S998). 



7. GYMNOTHAMNION J. Ag. Anal. Alg. 27. 1892. 



1. Gyxtmothanmion elegans (Schousb.) J. Ag. loc. cit. 178. 



Callithamnion elegans Schousb.; Ag. Sp. Alg. 2: 162. 1828; Born. & Thur. 



Not. Alg. 32. pi. 10. 1S76. 

 Ftilota Schousboei Born, in Born. & Thur. loc. cit. 34. 

 Flumaria Schousboei Schmitz; Born. MSm. Soc. Sci. Cherbourg 28: 330. 



1892. 

 ? Gymnothamnion bipinnatum Collins & Hervey, Proc. Am. Acad. 53: 139. 



pi. 4. f. S6. 1917. 

 ? Ptilothamnion bipinnatum M. A. Howe, in Britton, Fl. Bermuda 525. 

 1918. 



The main branches are simply pinnate and the opposite ramuli are usually 

 longer than in Bermudian specimens described as G. bipinnatum but not alto- 

 gether dissimilar conditions occur in the Bermudian type and the species is 

 probably the same. The Bahamian specimens, like the Bermudian, appear to 

 bear only tetrasporangia (tripartite), and pending the discovery of antheridia 



