and Genera of Chlorospermous Algse. 413 



b. Filaments not enclosed in gelatine having a defined form. 



3. Spirillum. (S. Jenneri, Hassall, 277. t. 75. f. 5.) 



4. Aphanizomenon. (A. incurvum, Hassall, 280. t. 76. f. 6.) 



5. Spluwozyga. (S. Carmichaelii, Harvey, t. 113.) 



6. Spermosira. (S. Harvey ana, Harvey, 1. 173.) 



Suborder IV. Phyllomorpha. 



Cells united together side by side, forming an expanded flat 

 or tubular frond; the cells parting into four, eight, or sixteen 

 cells by transverse and longitudinal section. 



Fam. Ulvaceae. 



"Cells divided vertically and horizontally, so as to make a 

 frond-like or tubular membrane. Propagation by zoospores 

 furnished with flagelliform cilia." (Berkeley, p. 162.) 



a. Frond and endochrome purple. 



1. Porphyra. Frond leaf-like, flat. (P. vulgaris, Harvey, Ph. Brit. 

 t.211.) 



2. Bangia. Frond filiform, tubular. (B.fusco-purpurea, Harvey, 

 Ph. Brit.) 



These genera, according to Thuret, have antheridia like Rho- 

 dosperms. (See Ann. Sc. Nat. Oct. 1856.) 



b. Endochrome and membranous frond green. 



3. Enteromorpha. Frond tubular, simple or branched, of a sin- 

 gle series of cells. (E. intestinalis, Harvey, Ph. Brit. t. 154.) 



4. Phycoseris. Frond membranous, of one series of small cells. 

 (P. Linza, Harvey, Ph. Brit. t. 39.) 



5. Dictyospharia. Frond membranous, of one series of large 

 vesicular cells ; the cells are quaternately divided. (D.favulosa, 

 Harvey, Ner. Bor.-Am. t. 44 b.) 



6. Ulva. Frond membranous, of two strata of small cells. ( U. 

 lactuca, Harvey, Ph. Brit. t. 243.) 



c. Endochrome and gelatinous frond green. 



7. Tetraspora. {T. Ulrica, Hassall, 300. t. 78. f. 10.) 



8. Prasiola. (P. calophylla (Ulva), Hassall, 298, t. 677. f. 1.) 



9. tMerismopoedia. (M. punctata, Hassall, 299. t. 84. f. 6.) 



Greville observes that sometimes there is only a single line of 

 quaternate granules in the narrowest frond, and as many as ten 

 or twelve in the broadest, of Ulva calophylla (see Algae Brit. 176), 

 and he states that the same difference occurs in Bangia, giving 



