SPIROGYRA. 219 



Occurring in small coves, shores of river, Bethlehem, 

 Pennsylvania. 



Syn. Spirogyra setiforme, var. incequalis, Wolle. Bull. Tor. Bot. 

 Club, 1883. 



Specimens were furnished to Witt, and Nord.'s Algce Ex- 

 siccatce; vide No. 541. 



SPIROGYRA CRASSA, Kg. 



Diameter of vegetative filaments, 150-156 yw; cells 1-1 2 -2 

 times longer than the diameter ; spirals numerous, four or 

 more, dentate or tuberculate, often close, subtransverse, 

 making 2 to 1 to more turns in cell ; fertile cells like the 

 others, not inflated. Zygospores broadly oval, elliptic, 

 ovoid or subglobose. 



The type-form has the cells -2 times as long as broad ; 

 var. Heeriana, Naeg., has cells li-2 times as long as broad. 



This, the largest of the genus, is common in ponds and 

 sluggish river waters ; it forms in early Summer long lubri- 

 cous masses, of a bright green color, easily distinguishable 

 by the unaided eye ; later in the season it assumes a dirty 

 green color ; in this condition it may be found very abun- 

 dant in fruit. 



Syn. Zygnema serratum, Hass. ; Spirogyra Heeriana, (Naeg.) Kg. 

 Plate CXL, figs. 1-3, two sterile and one fruiting filament. 



SPIROGYRA JUGALIS, (Dill.) Kg. 



Diameter of filaments, 90-100 //; cells 1-1 times longer 

 than the diameter, somewhat constricted at joints; chloro- 

 phyl bauds 3-4, each making 1-2 turns. Fructiferous cells 

 somewhat inflated ; zygospore elliptical or oval ; membrane 

 even, brown at maturity, one-half more in length than the 

 diameter. 



Syn. Conferva jugalis. Dill.; Spirogyra setiformis, Petit; Spirogyra 

 decimina. Kg. 

 Pond waters. 

 Plate CXXXVIII, figs. 7, 8, sterile and fruiting filaments. 



SPIROGYRA SETIFORMIS, (Both) Kg. 



Diameter of vegetative filaments, 102-110 ^ ; cells equal 

 to 1^-2 times as long as wide ; chlorophyl bands four or more, 

 up to eight, margins irregularly notched, describing ?-l 

 turn each in a cell ; sporiferous cells not inflated ; zygospores 

 elliptical, sometimes appearing ovate or globose as they 

 change position in the cell ; diameter slightly less than the 

 cell. 



