1886.] 



MICKOSCOPICAL JOURNAL. 



143 



119. Genus Sphcerozyga Agardh. 



Filaments not (or rarely) vaginate, 

 in an amorphous, very diffluent muci- 

 lage, of indefinite form. Heterocysts 

 intercalate. Resting spores on both 

 sides of the one or two heterocysts. 



130. Genus CvUndrosperimim 

 Kiitzing. 



Plant like Sphcerozyg'a. Hetero- 

 cysts terminal, single. Spores sin- 

 gle, just below the heterocysts. 



131. Genus Aulosira Kirchner- 

 Filaments single, curved, enclosed 



in evident sheaths. Heterocysts in- 

 tercalate. Resting spores c^lindric, 

 not contiguous to the heterocysts. 



122. Genus Nodularia Mesteus. 

 Filaments distinctly vaginate. in a 



gelatinous, irregular stratum. Heter- 

 ocysts regularly intercalated. Spores 

 fuscous, or golden yellow, globose, 

 slightly compressed. 



123. Genus Chrysostig?na Nobis. 

 Filaments single, consisting: of or- 



bicular, vegetative cells, enclosed in 

 distinct sheaths. Heterocysts inter- 

 calate. Spores unknown. 



134. Genus Coleospermitni Kirch- 

 ner. 



Filaments composed of cylindrical 

 cells, enclosed in a distinct sheath. 

 Heterocysts terminal. Spores irreg- 

 ularly placed in the filaments. 



125. Genus ///'/i'/a Nobis. 



Filaments curved, several enclosed 

 in a sheath (or in the largest sheaths) . 

 Heterocysts single, intercalate. 

 Spores unknown. 



C. OsCILLARIEyE. GrOUp 5. 



Synopsis of Genera. 

 Fdaments distinctly articulated col- 

 orless ; macro and micro-gonidia. 



Crenot/iri.\\ 126. 

 Filaments short, bright green, at- 

 tached- Cha/?icesip/io?i^ 127. 

 Filaments free, single or in indefi- 

 nite layers. Lyngbya., 128. 

 Like Lyngbya^ but erect, in fas- 

 cicles. Symploca^i 139. 

 Like Lyngbya., but united in bun- 

 dles in a common sheath 



Microcolciis. 130. 



Like Microcoleus^ but erect, and 

 united in fascicles. Inactis., 131. 



I . Filaments in distinct sheaths., 

 mostly xvithont 7novement. 



126. Genus Crenothrix Cohn. 

 Filaments distinctly articulated, 



colorless, in sheaths closed at the ends. 

 Propagation by two kinds of goni- 

 dia, of which the larger (macrogoni- 

 dia) are produced by the breaking up 

 of the ends of the filaments into the 

 single cells, the smaller (microgoni- 

 dia) by the division parallel and at 

 right angles to the axis of the fila- 

 ments. Both kinds of gonidia accu- 

 mulate in the swollen end of the 

 sheath and germinate after breaking 

 through the latter. 



127. Genus C h am ce siphon A. 

 Braun and Grunow. 



Filaments short, attached, light 

 blue-green, with thin, but distinct 

 colorless sheaths. Propagation by 

 unicellular gonidia. 



128. Genus Lyngbya Agardh em 

 Thuret. 



Filaments not attached, single or 

 often forming a membranous, con- 

 sistent shapeless layer, variously col- 

 ored ; sheaths distinct, each contain- 

 ing onl}' one filament. Propagation 

 by germinating filaments which creep 

 out of the sheaths and develop new 

 plants. 



129. Genus Symploca Kiitzing. 

 Filaments in sheaths like Lyngbya., 



but several united in small, upright 

 lumdles, which generally form larger 

 fascicles. 



130. Genus Microcoleus Desma- 

 zieres em Thuret. 



Filaments as in Lyngbya^ but 

 several or many united in a bunch 

 and enclosed in a common sheath, 

 which is either open or closed at the 

 end, and which usually separates in 

 fine branches. Bunches single or 

 united in formless membranous layers. 



131. Genus Inactis Kiitzing em 

 Thuret. 



Filaments as in preceding genus, 

 several in a common sheath (at least 

 in the larger sheaths) , but upright, 



