F. Børgesen: Rhodophyceæ of the Danish W. Indies. 



259 



cimens found here are small, seldom more than 5 cm. high 

 (Fig. 251). 



Plants with tetrasporangia as well as with antheridia and 

 cystocarps are found. 



The tetrasporangia (Fig. 252) are formed in the ramuli, mostly 

 in their upper ends, often, however, in ^U of their length. The 

 lowest sporangia are the oldest ones. Often, 

 too, the summit of the branch from which 

 the ramuli issue, is sporangiferous. The dia- 

 meter of the tetrasporangia is about 110 ju. 



The antheridial stands are placed in 

 the upper end of the ramuli (Fig. 252), 

 later also upon the summit of the main 

 filament itself. 



The cystocarps are placed scattered 

 upon the ramuli and upon the upper end 

 of the main axis (Fig. 251). The cystocarps 

 are ovate ■ — spherical about 1 mm broad 

 and 700/^ high. 



Some few larger specimens were dred- 

 ged in a depth of about 30 meters; these 

 specimens were upon the whole more slen- 

 derly built, and the ramuli had only 

 1 — 3 cystocarps each. 



St. Croix: Behind Long Reef near Christiansted. St. Jan: Off Cruz Bay. 



Geogr. Distrib.: Warmer parts of the Atlantic coasts of Europe and 

 America, Mediterranean Sea. 



Acanthophora Lamouioux. 



1. Acanthophora spicifera (Vahl) Borgs. 



Børgesen, F., Some new or Uttle known West Indian Florideæ, II 

 (Bot. Tidsskr.. 30. Bd. 1910, p. 201). 



Fucus spiciferus Vahl, Endeel kryptogamiske Planter fra St. Croix 

 (Skrivter af Naturhistorie-Selskabet, 5. Bd., 2. Hefte, 1802). Esper, Icones 

 Fucorum, 7. Heft, Nürnberg 1808. p. 108, tab. CLIX. 



Fucus acanthophorus Lamx., Dissertation sur quelques espéces de Fucus, 

 Agen, An XIII (1805) p. 61, pi. XXX et XXXI, fig. 1. 



Acanthophora Thierii Lamx., Essai sur les genres de la famille des 

 Thalassiophytes non articulées, Paris 1813, p. 44. Harvey, Nereis Boreali- 

 Americana, Part II, p. 7, pi. XIV. J. Agardh, Spec. Alg., vol. II, part 3, 

 Lund 1863, p. 819. 



Chondria acanthophora C. Ag., Spec. Alg., 1821, p. 363; Systema Alga- 

 rum, 1824, p. 209. 



17* 



Fig. 252. Chondria dasy- 



phylla (Woodw.) Ag. 

 Branchlets with tetra- 

 sporangia and antheridial 

 stands (About 12:]). 



