216- 



.ALG^ 



meiitary alternation of generations ; and Peter asserts (Bof. "Verein 

 Miinchen, Feb. 28, 1887) that the sexual form of Lemanea fluviatilis (Ag.) 

 may develop out of heteromorphic branches of a Chantransia. 



Literature. 



Wartraann—Beitr. zur Anat. und Jintwick. der Lemanea, 1854. 



Sirodot— Ann. Sc. Nat., xvi., 1872, p. 5; 1873; p. 241 ; and Compt. Rend"., Ixxix., 



1874, p. 1366. 

 Ketel— Anat. Untersuch. iiber Lemanea, 1887. 



The PoRPHYRACE^ Or Bangiacese are marine or fresh-water Algse 

 belonging to the two genera Porphyra (Ag.) and Bangia (Lyngb.). They 

 are regarded by some authors as much lower in structure than the red 



Fig. 193. -a, b, Bangia ceramicola 

 "Chauv. Portions of barren and fertile 

 "filaments ( x 330). (After Thuret.) 



Fig. ^<l,i,.—B,y'usco-puyp7trea Lyngb. Filament 

 in different stages of development (x 200). 

 (After Kiitzing.) 



seaweeds, but are best placed at present, from their mode of sexual 

 .-reproduction, as one of the lowest famihes of Floridese. The thallus is 

 -either fihform (Bangia), or is a thin transparent plate (Porphyra) com- 



