SPIROGYRA. 213 



diameter. Sporiferous cell slightly, or not at all swollen. 

 Color of mass deep green, slippery to the touch. 



Not infrequent in wet places, Florida. 

 Plate CXLI, figs. 3, 4, sterile, and fruiting filaments. 



SPIROGYRA QUININA, (Ag.) Kg. 



Deep green, slippery, diameter of filaments, 33-40 //. 

 Sterile articles 1-2 or rarely 6 times longer than broad ; fer- 

 tile cells 1-1 i diameters, scarcely or not at all swollen; 

 spiral single, the turns in various stages of density or of 

 laxity ; commonly 1 or 3 turns. The zygospores vary much 

 in form, apparently, some of them being globose, others 

 elliptic, and still others cylindrical with obtusely rounded 

 ends. 



$yi\. Zygnema qmninum, Ag. ; Conjugata condensata, Yauch. 



One of our most common forms in sterile condition ; fruits 

 in proper season very profusely ; occurs sometimes in masses, 

 all fruit. Many spore-bearing cells without evidence of 

 conjugation. 



Plate CXXXIY, figs. 14-17, sterile and fruiting filaments. 



SPIROGYRA COMMTJNIS, (Hass.) Kg. 



Diameter of vegetative filaments, 20-22 /* ; cells 3-5 times 

 longer than broad ; spiral slender, lax, describing l*-4 turns. 

 Fructiferous cells not dilated ; zygospores elliptic, changing 

 from green to yellow at maturity, 2-3 times longer than 

 broad ; diameter 19-23 /*. 



Syn. Zygnema commune, Hass. ; Zygnema reversum, Hass. ; Rhyn- 

 chonema reversum, Kg. 

 Ponds and ditches. 

 Plate CXLII, figs. 1, 2, sterile and fruiting filaments. 



SPIROGYRA JURGENSII, Kg. 



Diameter of vegetative filaments, 24-26 yw; cells 2-i-5 

 times longer than broad ; spiral slender, light green. Spore- 

 bearing cells gently swollen around the elliptic zygospore, 

 which is twice as long as wide; diameter about 30 yu, 

 changes color to golden yellow at maturity. 

 Stagnant and sluggish waters. 



The distinction between this and.,& communis is slight, 

 resting almost altogether on the swollen fructiferous cells. 



Plate CXLII, figs. 3, 4. 



