232 American Quarterly Microscopical Journal. 



through which the contents of one cell pass over into 

 the other. Spores spherical or elliptical. Spore-cells 

 turgid. Numerous species. 



a. One band of chlorophyll in each cell. 



a. Cell-ends folded in. 



Sp. tennissi/na, Ktz. Cells 0.007 — 0.008 d.; l. = 5 — 8 d. Chloro- 

 phyll band with 4-5 turns. Spores elliptical. Common. 

 Sp. ventricosa, Ktz. Cells 0.02 d.; bands with 3-6 turns. 



\*Sp. Weberi, Ktz. Sterile joints 3-20 times longer than broad, 

 fertile joints not swollen, band usually single, 3-8 turns. 



*Sp.protecta, Wood. Spore-wall very thick, 6 turns. Sterile joints 

 6 times longer than broad.] 



ft. Cell-ends not folded in. 

 *Sp. quinina, Ag. Cells 0.03 — 0.04 d ; l. = i to 2 d.; band with 



about 3 turns. 

 ^Sp. longata, Ktz. Cells 0.02 — 0.025 d.; l. = 2-8 d.; band with 2- 



4J^ turns. 



b. Several chlorophyll bands in each cell, often crossed. 

 a. Cell-ends folded in. 



*Sp. insignis, Ktz. Cells 0.027 — 0.03 d.; l.=4-6 d.; 3 very attenu- 

 ate bands with i — lyi turns, [rarely 3.] 

 /?. Cell-ends not folded in. 

 *Sp. deci/nina, Ktz. Cells 0.03-0.036 d.; l.=2-4 d. Bands with 



2-2^ turns. 

 *Sp. setiformis, Ktz. Cells 0.08-0.1 d.; l. = d., drawn in some- 

 what at the ends. Bands very closely wound. [3-8 

 bands.] 

 *Sp. nitida, Ktz. Cells 0.055-0.07 d.; l.= i-2 d.; 4-5 steeply- 

 wound bands. Outer membrane mucilaginous. 

 *Sp. crassa, Ktz. Cells 0.12-0. 13 d. (and over); 1.^^-2 d.; 

 4 bands slightly constricted at the ends. 

 \*Sp. diluta, Wood. Chlorophyll bands 5, very narrow, more resem- 

 bling nodules with fine connecting threads, >^-i turn. 



*Sp. dubia, Ktz. Sterile joints Yz-iYz times longer than broad ; 

 2-3 very narrow bands, nodose, 1-2 turns. Zygospores polymorphous. 

 "^Sp. parvispora. Wood. Sterile joints 2-4 times, and fertile 1-2^ 

 times longer than broad ; 4 bands, narrow, nodose, many turns. 



*Sp. majicscida, Ktz. Pale green, fuscescent while fruiting, 3-4-5-7 

 bands, partly straightish and longitudinal, nodose.] 

 3. Gen. Zygnema, Ktz. Cells with two star-shaped plates of 

 chlorophyll, each with a starch grain, copulation as in 



