492 Howe : Phycological studies 



and H. Tiina, using for her studies of the latter, through the 

 courtesy of M. Ed. Bornet, " a portion of the identical specimen " 

 described by Derbes & Solier. Mrs. Gepp in this paper brought 

 out some especially interesting facts in regard to the relation of 

 the sporangiophores to the filaments of the central strand. 



In 1905, in distinguishing the newly recognized species Hali- 

 meda scabra, an ally oi H. Tuna horn Florida and the Bahamas, the 

 present writer * described and figured its sporangia and alluded to a 

 fertile specimen of H. Ttina collected in Bermuda. In view of the 

 rarity of the occurrence of fertile specimens in this genus, it may 

 be remarked that the Bermuda specimen was found in the month 

 of June and the Florida specimen of H. scabra on March 30. 



In each of these cases only a single plant out of the many 

 observed was fertile. But on March 3, 1906, near the mouth of 

 the main harbor of Culebra Island, Porto Rico, the writer found, 

 growing near the low-water mark, an abundance of Halimeda 

 Tuna laden with sporangia. The photograph published herewith 

 (pL. 27, FIGS. 2-4) gives an idea of the appearance of these fer- 

 tile specimens and of the position of the sporangia upon them. 

 The sporangia occur chiefly in crowded clusters on the margins of 

 the segments, but they are also often scattered over the discs or 

 flattened faces of the segments, which they occasionally cover 

 almost completely. Derbes & Solier and Mrs. Gepp describe and 

 figure the sporangia of Halimeda Tuna as occurring only on the 

 margins of the segments, but Zanardini both describes and illus- 

 trates them as occurring also on the discs. The sporangiophores 

 are 1-2 mm. long and both in these Porto Rican and in the Ber- 

 mudian specimens they are apparently rather more simple (pl. 25, 

 FIGS. 7-9 ; PL. 28, FIGS. I and 2) than those of the European H. 

 Tuna; at least, we have never observed the forking which Mrs. Gepp 

 has described and figured (/. c.,f. 6) as occurring immediately after 

 the fusion of their basal filaments. All the sporangiophores that we 

 have seen are either simple or once dichotomous near the top — 

 somewhat resembling Derbes & '^oXxo.x' s figure 2. Those spring- 

 ing from the margins of the segments (pl. 25, figs. 8, 9, 10) are 

 formed by the fusion of two or three filaments of the central strand, 

 but those springing from the discs or flattened faces come directly 



*Bull. Torrey Club 32 : 241-244. //. //, 12. 1905. 



