[From the Bulletin of the Torrey Botanical Club 34: 491-516, //. is-jo. 1907] 



Phycological studies — III. Further notes on Halimeda and 



Avrainvillea 



Marshall Avery Howe 

 (with plates 25-30) 



A. On the sporangia of Halimeda tridens and of 



Halimeda Tuna 



The sporangia of the genus Halimeda were for many years 

 known only in the single species Halimeda Tima* though in 1876 

 Zanardini t briefly described those of H. macroloba and in 1880 

 Schmitz X contrasted the characters of the sporangiophores of 

 Halimeda Tuna with those of H. platydisca. But the true Hali- 

 meda platydisca Decaisne, according to the original preserved in 

 the Museum d'Histoire Naturelle of Paris, appears to be simply a 

 large form of H. Tuna,% and whether Schmitz was really dealing 

 with two distinct species or with two forms of H. Tuna is not 

 altogether clear. In 1904, Mrs. Gepp || described and illustrated 

 in detail the sporangia and sporangiophores of Halimeda gracilis 



* DerWs & Solier, Suppl. Compt. Rend, i : 46, 47. //. //. /. 18-22. pi. 12. f. 



j-3. 1856. 



Bompard, Hedwigia 6 : 129. 1867. 



Zanardini, Mem. R. 1st. Ven. ig : 541-543. //. 30. 1876. 



•j" Zanardini, I. c. 543. 



% Sitzungsber. d. niederrheinischer Ges. f. Natur- und Heilkunde 1880 : 140-146. 



1880. 



\ Barton, E. S. The genus Halimeda. Siboga-Expeditie, Monographe 60 : 14. 



1901. The present writer, after examining the same type, concurs with the monog- 

 rapher of "The genus Halimeda" in the opinion that //. platydisca does not offer 

 any satisfactory characters in form or structure to distinguish it from H. Tuna. 



II Gepp, E. S. The sporangia of Halimeda. Jour. Bot. 42 : 193-197. //. 461. 

 1904. 



491 



