10 SYNOPSIS OF BRITISH SEAWEEDS. 



XCVr. Ulva. Frond Bat, ereen. 



.WVil. Pobphybi.. Frond flat, purple. 



XCVIII. Banoia, Frond filiform (mostly), purple or pink. 



Order 17. Oscillatoriace.k. Gfreen or blue, rarely purple, 

 marine or (more frequently) fresh-water Alga, composed 

 of continuous, tubular, simple, or rarely branching fila- 

 ments, which are either free or invested with gelatine. En- 



dochrome '(/undated, at length separating into lenticular 

 Bporidia. 

 Sub-order 1. Rivularie.e. Filaments united together into a 

 solid gelatinous or cartilaginous frond. 

 XCIX. RlVTJLARLA. Filaments not sheathed. 

 C. Schizosiphon. Filaments sheathed; the sheath mul- 

 tifid. 



Sub-order 2. Oscillatorie.e. Filaments tufted or stratified, 

 free. 



CI. Schizothrix. Filaments rigid, in branching bundles, 

 at length splitting. 



CII. Calothrix. Filaments short, tufted, fixed at the base 

 only. 



CIII. Lyxgbya. Filaments elongate, decumbent, flaccid. 



CIV. Microcoleus. Filaments needle-shaped, several en- 

 closed together in membranous or gelatinous sheaths. 



CV. Oscillatoria. Filaments needle-shaped, straight or 

 slightly curved, short, heaped together in gelatinous 

 strata, oscillating. 



CVI. Spirulixa. Filaments spirally twisted, lying in a 

 mucous stratum, vividly oscillating. 



Order 18. Xostochaceje. Green, fresh-water or rarely marine 

 Algce, composed of moniliform filaments, Iging in a gela- 

 tinous matrix. Cells globose or oval. 

 CVII. Moxormia. A single filament enclosed in a convo- 

 luted gelatinous and branching frond. 

 CVIII. Spr\erozy~oa. Filaments free, separate, naked. 

 CIX. Spermosira. Filaments free, separate; each enclosed 

 in a very delicate, membranous, filiform tube. 



Order 19. Palme llace^:. 



Sub-order Hormospore.e. Cells contained in confervoid, sim- 

 ple or branching, tubular filaments. 

 CX. HoRMOSPORA. 



