GOMPHOSPHAERIA Kuetzing 1836, Dec. XVI, No. 151 

 A globose or ovate colony of globular or pyriform cells arranged 

 singly or in pairs at the ends of gelatinous strands which radiate 

 from a common center, the cells at the periphery of a colorless, 

 mucilaginous envelope; individual sheaths o'f the cells usually con- 

 fluent. 



Following cell division in this genus, the cells lie side by side in 

 pairs (or in 4's) for some time. The division is accompanied by a 

 forking of the stalk at base of cell, which thus forms the radiating 

 branched stalks of the colony. The cells, especially in some species, 

 appear heart-shaped because fission begins at the outer, free pole 

 of the cell, whereas division of the attached end of the cell is delayed. 



Key to the Species 



Cells 4-l2fi in diameter (some varieties 



smaller), pyriform or cordate G. aponina 



Cells 1.5-2.4^1 in diameter, spherical or somewhat reniform G. lacustris 



Gomphosphaeria aponina Kuetzing 1836, Dec. XVI, No. 151 



PI. 106, Fig. 5 

 Cells pyriform, or cordate in stages of division, arranged at the 

 periphery of a globular and usually wide gelatinous sheath, and at 

 the ends of stout radiating, gelatinous strands; cells 4-5/a in diam- 

 eter, 8-12/A long. 



Tychoplankter; common in many lakes. Mich., Wis. 



Gomphosphaeria aponina var. cordiformis Wolle 1882, 

 Bull. Torr. Bot. Club, 9, p. 25 

 PI. 106, Fig. 6 

 Cells decidedly cordate, compactly arranged within a thick gela- 

 tinous envelope, individual sheaths distinct; cells 6-l2ix in diameter, 

 12-15- (20)^ long. 



Occurring with the typical plant. Mich., Wis. 



Gomphosphaeria aponina var. delicatula Virieux 1916, p. 69 



PI. 106, Fig. 7 

 A variety differing from the typical by the smaller size of the 

 cells, which are 2-3.5/a in diameter, 4.5-6/x long; colonies globose 

 or ovate and often lobed. 



Euplankter; uncommon. Wis. 



[472] 



