dt) WISCONSIN PHYTOPLANKTON 



(r), Otter (rr), Paddock (c), Palmer (SB), Pardee (rr), Pewaukee (ss), 

 Plum (ss), Pokegama (1) (c), Pokegama (2) (sss), Pokegama (3) (a), Pop- 

 lar (r), Prairie (s), Reserve (ss), Rainbow (r), Rice (1) (cc), Rock (a), 

 Rooney (aa), Round (1) (rrr), Round (2) (ss), Round (3) (ss), St. Croix 

 (cc), Sanford (r), Sand (1) (ss), Sand (2) (rr), Sand (3) (rr), Sand (4) 

 (rr), Silver (2) (c), iSishebogema (aa), South Turtle (sss), Upper Nashotah 

 (rr), Upper Nemahbin (rr), Upper Turtle (s), Wapagossett (cc), Waubesa 

 (cc), White Ash (rr), Whitefish (cc), White Sand (rrr), Wildcat (rrr), Win- 

 ncbago (cc),Wolf (rrr). 



The radial fibrillar structure at the periphery of the gelatinous en- 

 velope is also found at times in the center of the colony. These radia- 

 tions have been compared by some to the gelatinous strands found in 

 Gomphosphaeria and the species transferred to that genus. I have 

 preferred to keep the alga in the genus where it was first described. 

 This alga is one of the important members of the Myxophyceae in the 

 formation of blooms but it is rarely found as the sole constituent of 

 any bloom. Bachmann's figures of the alga are quite characteristic. 



GOMPHOSPHAERIA Kiitzing 1836. 



Colonies microscopic, spherical to ellipsoid, embedded in a copious, 

 hyaline, solid, homogeneous, gelatinous envelope. Cells spherical 

 to pyriform, solitary or in pairs, generally lying some distance from 

 one another and forming a layer one cell in thickness towards the pe- 

 riphery of the colonial envelope. Central portion of colonial envelope 

 containing a denser core from which projections radiate to the base of 

 the cells. Individual sheaths of cells distinct or confluent with the 

 colonial envelope. Cell contents homogeneous, rarely granulose; grey 

 to light or bright blue-green. 



Reproduction by alternate vegetative division of cells in three planes. 



KEY TO THE SPECIES. 



Cells spherical G. LACUSTBIS 



Cells pyriform to cardioid G. APONINA 



GOMPHOSPHAERIA LACUSTRIS Chodat. PI. 4, Fig. 5. 



Bull. Herb. Boiss. 6: 180, figs. 1 A -1 G . 1898; W. & G. S. West, Trans. Roy. Irish 

 Acad. 33, Sec. B: 112, pi. 11, figs. 24-27. 1906. 



Colonies small, generally spherical or subspherical, rarely reniform; 

 with a hyaline, homogeneous, gelatinous envelope. Cells spherical to 

 broadly ellipsoid, irregularly spaced to form a single layer one cell in 

 thickness beneath the periphery of the colonial envelope. Individual 

 cell sheaths confluent with colonial envelope. Central portion of col- 

 ony containing a core of denser radiating gelatinous strands that run 



