SPIROGYRA. 209 



Kirchner makes the following varieties of this species : 



a. genuina, Kirch. Cells four to eight times as long as 

 broad ; one spiral making 3-5 turns. Diameter of 

 cells, 16-22 jw. 



b. elongata, Rab. Cells 4-14 times as long as broad; one 

 spiral, 2-5 2 turns. Diameter as the last. Plate 

 LXX, figs. 1, 2. 



c. Httseana.; Kab. Two spirals, otherwise like "a." 



d. intermedia, Kg. Cells twice as long as broad ; copulation 

 usually lateral. 



e. tennis, Eab. Filaments thinner than any of the other 

 forms. Ehynchonema Jenneri, Kg. 



Syn. Spirogyra Hornschuchii, Kerst. ; Zygnema longatum ; Zygnema 

 intermedia, Hass. ; Spirogyra elongata, Wood. 

 Appears widely and liberally distributed in quiet waters. 



Plate CXXXII, fig. 11. 



% 



SPIROGYRA GREVILLEANA, (Hass.) Kg. 



Diameter of vegetative filaments, 28-33 // ; cells 3-10 times 

 longer than broad ; ends inlaid ; spiral usually single, more 

 rarely double, describing 4-5, or occasionally 6-9 turns ; 

 when two spirals the turns are more numerous ; fructiferous 

 cells considerably swollen. Zygospores oval, brownish yel- 

 low when mature, 2-2 i times longer than the diameter, vary- 

 ing from 30-36 JA. 



Var. DIDUCTA, Kg. ; Zygnema diductum, Hass. , and Z. vesicatum, 



Hass. 



Cells 3-4 times longer than wide ; fructiferous cells much 

 inflated. 



This species is separated from S. Weberi by the larger size 

 of filaments, usually shorter cells and especially by the in- 

 flated spore-bearing cells. 



Syn. Zygnema Grevilleana, Hass.; AS. inaequalis, Kg.; Rhyncho- 

 nema diductum. Kg. 



Occurs frequently in sluggish and stagnant waters. 

 Plate CXXXII, figs. 12, 13, sterile and fruiting filaments. 



b. Membrane of spore punctate. 



SPIROGYRA CALOSPORA, Cleve. 



Diameter of vegetative filaments, 36-40 /*; 6-12 times 

 longer than broad; spiral single, slender, describing 4-5 



