CEEAMIACEAE. 581 



and oystoearps, the generic position of the plants must remain in some doubt. 

 There are discrepancies between Bornet's and J. Agardh's figures of the oysto- 

 carp of Gymnothamnion elegans and the relation of Gymnothatrmion to Ptilo- 

 thamnion TPould seem to be in need of further study. 



Forming a thin coating on rocks a little above the low-water mark, Gun Cay : — 

 northern Africa and Mediterranean sliores of Europe; Bermuda (?). Type from 

 Tangier, Morocco. 



8. ANTITHAMNION Nag. Neu. Algensyst. 200. 1847. 



Main axes 24-30 « in diameter, for the most part regularly bi- 



pinnate. 1. A. Butleriae. 



Main axes 75-150 u in diameter, their branches tetrastichous, the 



ultimate branchlets often alternate or subdisticbous. 2. A. cruciatum. 



1. Antithamnion ButlSriae Collins, Proe, Am. Acad. 37 : 258. 1901. 



The fronds in Bahamian specimens are broader and the cells are usually 

 longer, both actually and relatively, than in the type form. 



On a rock shelf under an overhang, between the tide-lines, and washed ashore. 

 Rose Island, Exuma Chain, and Caicos Islands : — Jamaica and Barbados. Type from 

 Kingston, Jamaica. 



2. Antithamnion cruciatum (Ag.) Nag. Neu. Algensyst. 200. 1847. 



With Jania, washed ashore, Great Bahama : — Massachusetts and Bermuda to 

 Barbados ; Europe. Type from Trieste. 



9. OBOUANIA J. Ag. Alg. Med. et Adxiat. 83. 1842. 

 1. Crouania attenusita (Bonnem.) J. Ag. loc. cit. 



Satraohospermum attenuatum Bonnem. fide Ag. 

 Mesogloia attenuata Ag. Syst. Alg. 51. 1824. 



On various algae, Thalassia, etc., from near low-water mark down to 20 meters 

 (fide Borgesen), New Providence, Berry Islands, Joulter's Cay, Great Bahama, Wat- 

 ling's Island, and Mariguana : — Bermuda and Florida to Barbados ; southern EJurope. 

 Type (in herb. Ag.) from northwestern Prance (" Armorica "). 



10. SPYEIDIA Harv. in Sm. Eng. Fl. 5': 336. 1833. 



Bamuli without lateral uncinate spines. 1. 8. fllamentosa. 



Ramuli normally with one or more uncinate spines on the distal 



nodes. 2. S. aculeata. 



1. Spyridia filamentdsa (Wulf.) Harv. loc. cit. 337. 



Fuous filamentosus Wulf. Crypt. Aquat. 64. 1803. 



Spyridia occidentalis Kiitz. Sp. Alg. 666. 1849. 



Spyridia apiculata Kiitz. Tab. Phyc. 12: 15. pi. 4.9. f. o, d. 1862. 



Common In shallow warm water. Rose Island, Berry Islands, Great Bahama, 

 Bimini, North Cat Cay, Exuma Chain, Cat Island, and Caicos Islands : — Massachu- 

 setts and Bermuda to South America ; widely distributed in the warmer seas. Type 

 from the Adriatic Sea. 



2. Spyridia aculeata (Schimp.) Kiitz. Phyc. Gen. 377. 1843. 



Ceramium aculeatum Schimp. in Unio Itin. no. 966 (not seen). 



On rocks and on other algae in shallow water or down to 30 meters (fide 

 Borgesen), Berry Islands, Great Bahama, Gun Cay, and Mariguana: — Bermuda and 

 Florida to American Virgin Islands ; southern Europe and northern Africa ; Red Sea. 

 Type from the Red Sea. 



