226 FRESH-WATER ALG^E OF THE UNITED STATES. 



when fully matured, dull -olivaceous ; sporoderm punctate 

 or scrobiculate. 



In stagnant waters. 



Syn. Conjugata pectinata, Vauch. ; Conferva decussata, Dillw. ; 

 Tyndaridea conspicua, Hass. 



Plate CXLV, figs. 1, 2, sterile and fruiting filaments, with 

 three perfected spores and two forming. 



ZYGOGONIUM AEQUALE, (Kg. ) Wolle. 



Diameter of vegetative filaments, 30-33 // ; cells 1-2-3 

 times as long as wide; zygospores not as long as wide, 

 measuring 25 by 30 yw, transversely oval. 

 Marsh pools, Pennsylvania. 



Syn. Zygogonium saxonicum, Eab. 



Eabenhorst quotes this species in his Flora Algarum, but 

 fails to give the size or form of the zygospore the dis- 

 tinguishing feature; we assume the name, however, at a 

 hazard, as it agrees so well in proportionate length and 

 breadth of cells. 



Plate CXLY, fig. 3. 



. 



ZYGOGONIUM DECUSSATUM, (Vauch.) Kg. 



Diameter of vegetative filaments, 18-20 /* ; cells 3-5 times 

 longer than broad ; cell membrane thin ; connecting tube 

 inflated, bearing a spherical zygospore; somewhat larger 

 than the diameter of the filament. 



Ponds, sluggish or stagnant waters. 



Syn. Tyndaridea decussata, Hass. ; Conjugata decussata, Vauch. 



Plate CXLV, figs. 4, 5, conjugating filaments with cells 

 partly sterile, partly with zygospores. 



ZYGOGONIUM AGARDHII, Eab. 



Diameter of filaments, 15-18 yu; cells 1J-2 times longer 

 than broad, more rarely equal ; bright yellow green, cells 

 not swollen; sometimes moderately constricted at joints; 

 zygospore globose, rarely slightly oval, membrane firm, 

 colorless, smooth ; diameter, 20-25 //. 

 Wet ground, Florida, frequent. 



Plate CXLV, figs. 6, 7, fruiting filaments. 



In size the plants ascribed to this species are thinner than 

 those of Z. compicuum, Kg., nearer Z. decussatum, Kg.; the 

 articulations are longer than the average of the former, and 

 shorter than those of the latter. 



