SPIROGYRA. 211 



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SPIROGYRA HANTZSCHII, Eab. 



Diameter of vegetative filaments, 40-45 yw ; cells 3-5 times 

 longer than broad ; spirals two, making two or three turns 

 in shorter cells. Spore-bearing cells not at all swollen; 

 spores twice as long as wide. 



This plant is near the preceding in size, length of cell and 

 form of spore ; but separated by having only two spirals 

 and by fruit-bearing cells not being inflated. 



Stagnant waters, Pennsylvania. 



Plate CXXXIII, figs. 10, 11, filaments conjugated, with 

 spores, and sterile filaments. 



SECTION II. MEMBRANE OF CELLS NOT REPLICATE 



AT THE ENDS. 



A. One spiral in each cell, 

 a. Zygospores having membrane smooth. 



SPIROGYRA MIRABILE, Hass. 



Diameter of vegetative filaments, 24-27 /* cells 4-10 

 times longer than broad ; spiral single describing 4-7 turns 

 in cell. Fruiting cells considerably inflated. Conjugation 

 lateral more frequently than scalariform. Zygospore li-2 

 times longer than the diameter. Shorter axis varies from 

 24-26 /*. 



Syii. Zygnema mirabile, Hass. ; Spirogyra mirdbilis. Kg. 



The only specimens had for examination were from Wis- 

 consin. 

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



SPIROGYRA FLAVESCENS, (Hass.) Cleve. 



Diameter of vegetative filaments, 13-20 ja ; cells 3-5 times 

 longer than broad ; spiral single, yellow green, describing 

 2-3 turns. Fructiferous cell much swollen, spore 25 by 40 //. 



Syn. Zygnema flavescens, Hass. ; Zygnema affine, Hass. ; JRhyncho- 

 nema affine. Kg. 



Picked up satisfactory specimens of this species, fre- 

 quently in stagnant waters in Florida. It averages some- 

 what larger than the French form, but conforms well with 

 English specimens. 



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



SPIROGYRA GRACILIS, (Hass.) Kg. 



Diameter of vegetative filaments, 18-22 // ; cells 3-5 times 

 longer than broad ; spiral bright green, making i-3 turns ; 



