oo. Filaments in tufts in a dense gelatinous substance (fig. 



27)- Chaetophom. 



nn. Filaments and main branches large, bearing tufts of small 



branchlets (fig. 32). Drapanialdia. 



jj. Filaments not branched. 



k. Cells with thick lamellose coats, in a series inside a lauiellose 



sheath. Cylindrocapsack.I', Cyliudrocapsa. 



kk. Cells without lamellose coat. Ui.othrichacK/E. 



I. Filaments attached, chromatophore a homogeneous zonate 



baud, with one to several pyrenoids (fig. 29). Ulothii.v. 



II. Filaments usually not attached, and chromatophore of a 



difference character, 

 m. Chromatophore a parietal disk or plate, with one pyrenoid. 



Stichococciis. 

 mm. Chromatophore granular, covering more or less com- 

 pletely the whole cell wall, containing starch but no 

 pyrenoids (fig. 2S). Microspora. 



lib. Filaments not ending in a bristle, 

 i. Chloroplasts numerous, parietal, each with a pyrenoid (fig. 24) 



CLADOPHORALEvS. Cladoplwm. 



ii. Chloroplasts single or several, large and of some definite shape, 



with pyrenoids. The entire contents of two cells unite to 



form a single zygote. CONJUGAT.F;.* 



j. Thallus a thread of many similar cells, each zygospore produces 



only one germ plant. Zygnemace-iJ. 



k. Chloroplast of spiral bands, (fig. 17). Spirogyra. 



■ kk. Chloraplasts not spiral. 



I. Chloroplasts consist of two stellate bodies for each cell (^fig. 



20). Zygneuta. 



II. Chloroplast an axile plate, (figs. 18, 19) iMoiigrolia. 

 jj. Unicellular, rarel}- bound together in a loose thread. 



DesmidiacE.^. (See page 8). 

 bb. Organism yellowish green, red or brown. 

 c. Organism yellowish green. HETEROKONTJE. 



d. Plants unicelhdar. C/iloro/wtrys, Ophiocytiinn (fig. 15). 



dd. Plants filamentous, cell wall firm, splitting into H-shaped pieces 

 (fig. 31). Triboneiita {= Co!//ri-z'a). 



cc. Organism grayish or brownish or aml)er colored, 

 d Unicellular organisms consisting of two silicious valves. 



BACILLARIACEiE [^ Diaioins) vSec jiage 10. 

 dd. Cells neither silicious nor two valved. (vSee illustration \n. 



PHiEOPHYCEiE. 

 A part of this group is included by the zoologists in the class INIasti- 

 gophora among the Protozoa. The forms most freciuently met with may be 

 distinguished as follows. 



e. With two flagella, the smaller lies in a cross furrow, the other in a 

 longitudinal furrow. 



*The two orders Schizogotiiales and Microsporales are not re])resented in 

 our plancton. 



