HOWE AND HOYT: MARINE ALGAE FROM BEAUFORT, N. C. II3 



of reproduction. We have hesitated long before deciding whether 

 to refer this North Carohna plant to the genus Colaconema of 

 Batters, the genus Erythrocladia of Rosenvinge, or to establish 

 for it a new genus, differing from both of the named genera in its 

 sexual method of reproduction. One of us (M. A. Howe) has 

 recently^ expressed the opinion that Colaconema,^ or its type species, 

 C. Bonnemaisoniae, is "a close relative of Acrochaetium, near 

 which it was finally placed by Batters." However, a reexamina- 

 tion of a considerable number of specimens of Colaconema Bonne- 

 maisoniae, with special attention to the position and development 

 of the spores, convinces us that Colaconema is very closely allied 

 to Erythrotrichia and Erythrocladia, as has been suspected by 

 Rosenvinge. The " monosporangia " of C. Bonnemaisoniae are 

 mostly terminal on short branches and when their "cup-like" 

 base is not particularly well developed they may bear a superficial 

 resemblance to monosporangia of an Acrochaetium, but typically 

 the "sporangia" are subtended by a cup-like base, which may 

 embrace the sporangium or spore to its middle. And the spores 

 are not always terminal. They may be cut out from the side of 

 the terminal cell or from the side (often obliquely near the distal 

 end) of an ordinary or scarcely differentiated intercalary cell. 

 In origin and form their resemblance to the spores of Erythrotrichia 

 and Erythrocladia is most marked. Colaconema was described as 

 "living in the cell-walls of various algae," while Erythrocladia was 

 described as an epiphyte. But in specimens of E. irregularis, 

 the type of the genus Erythrocladia, which we owe to the courtesy 

 of Dr. Rosenvinge, its describer, the plant is clearly immersed 

 in the outer walls of its host, Polysiphonia urceolata. In mode of 

 reproduction and in habit of life there appears to be little differ- 

 ence between the type of Colaconema and the type of Erythrocladia. 

 However, in the type of Colaco?iema, the thallus is loosely fila- 

 mentous, with no observable tendency to radiate from any one 

 point as a center and no tendency to form a pseudoparenchyma ; 

 the filaments are chiefly, but not wholly, confined to the outer 

 walls of the superficial cells of its host; these filaments or their 



1 Mem. Torrey Club 15: 83. 19 14. 



2 Batters, Jour. Bot. 34: 8. Ja 1896. The homonymous genus Colaconema Schmitz, 

 in Eng. & Prantl, Nat. Pflanzenfam. i^: 452. 1907, has been renamed Colacopsis by 

 De-Toni, Syll. Alg. 4: 1170. 1903. 



