BOT.— Vol. I.] SAUNDERS— PHYCOLOGICAL MEMOIRS. 1 59 



Synopsis of Genera. 



Plant body undifferentiated — of similar structure throughout. 



Plant thin, a flat, leaf-like membrane Homeostrouia. 



Plant body differentiated — composed of at least two kinds of cells. 



Sporangia sunken beneath the surface, plant hollow, cylindrical, or club 



shaped Coilodesme 



Sporangia on the surface. 



Paraphyses none, plant a leaf-like membrane. 



Central layer of tissue composed of large, irregularly rounded 



cells Phyllitis. 



Central layer of tissue a loose web of slender branching fila- 

 ments Endarachne. 



Central layer of tissue composed of a smaller, compact layer of 



cells reproducing by unilocular sporangia Halorhipis. 



Paraphyses unicellular. 



Plant body hollow, cylindrical Scytosiphon. 



Plant body hollow, irregulary rounded or oval Colpomenia. 



Paraphyses multicellular ; plant body rounded or oval, plants mostly 

 aggregated Soranthera. 



30. Homeostroma J. Ag. 



Homeostronia J. Ac, Anal. Alg. Cont., Ill, 1896, 3. 

 Punctaria Grev., Syn. in Alg. Brit., XLII, 1830, (in parte.) 



Plant body membranaceous, of several (2-7) similar layers of cuboidal cells. 

 Unilocular and plurilocular sporangia oblong or oval, formed from the outer 

 layer of cells ; paraphyses none, furnished with numerous clusters of hairs. 



31. Homeostroma latifolium y. Ag. 



Plate XXX, Figs. 4 and 5. 



HonieostroDia latifolium]. Ac, 1. c. 



Punctaria latifolia, Born, et Thur., Etud., phycol. p. 13. 



Plant body arising from a minute disk, lanceolate-obovate, 1-5 dcm. long, 

 tapering below to a short stalk 2-10 mm. long, olive-green, plaited on the 

 edges ; tissue consisting of 4 or 5 rows of cells ; unilocular and plurilocular 

 sporangia scattered, on the same plant. 



Attached to leaves of Zostera marina washed ashore at 

 Monterey, California. 



32. Coilodesme Stroemf. 



Coilodesme Strcemf., King. Meersalg. Isl., 173, 1886. 



Plant body hollow, cylindrical or oval, on a short, solid stalk which arises 

 from a minute disk-like base composed of two (or three) layers of tissue, an 

 inner layer of large, mostly colorless, cylindrical cells and an outer layer of 

 smaller colored cells. Unilocular sporangia solitary, scattered, developed 

 from the outer layer of cells but surrounded by the continued growth of the 

 outer layer of tissue ; plurilocular sporangia, hairs, and paraphyses wanting. 



