48 WISCONSIN PETTOPLANKTON 



hundred cells. These cells are also proportionally longer than he states 

 and may be, in extreme cases, sixteen times as long as they are broad. 

 In this respect they follow the cell dimensions delimited by Lemmer- 

 raann. 



DACTYLOCOCCOPSIS ACICULAEIS Lemmermann. PI. 6, Figs. 8-10. 



Ber. d. D. Bot. Ges. 18: 309. 1900; Kryptogamenfl. d. Mark Brandenburg 3, 

 Algen 1: 51, 44, fig. 5. 1907. 



Cells solitary or in colonies enclosed by a wide, hyaline, homogeneous, 

 gelatinous sheath. Cells elongate, acicular, with poles attenuated to 

 fine points; straight or slightly arcuate. Cell contents homogeneous 

 and pale blue-green ; or with color bearing region restricted to one side 

 of cell. (Euplanktont). 



Cells 2-2.5 (i broad, 55-80 p. long. 



Browns (cc). 



The localization of the color bearing portion at one side of the cell is 

 quite abnormal for a member of the Myxophyceae, but, as I have stated 

 elsewhere (Trans. Wis. Acad. Sci., Arts, & Lett. 19 1 : 620. 1918) not- 

 withstanding this fact the alga belongs to the Myxophyceae. 



Order HORMOGONEALES. 



Cells always in filaments that generally contain a number of cells. 

 Filaments simple or branched; solitary or united to form definitely or 

 indefinitely shaped aggregates. Free-floating, sessile, epiphytic, or en- 

 dophytic. Cells serially arranged to form trichomes, which when en- 

 closed by a sheath are known as filaments. Trichomes either the same 

 thickness throughout, attenuated towards both extremities, or attenu- 

 ated from base to apex ; straight, arcuate, spirally or irregularly twisted. 

 Sheaths of filaments tough and leathery; or gelatinous, homogeneous 

 to lamellated, hyaline to variously colored, and distinct or confluent 

 with the colonial envelope. Cell shape various. Cell contents homo- 

 geneous, or with numerous pseudovacuoles ; grey, light to dark blue- 

 green, olive-green, reddish-green, ochraceous, orange, violet, or black 

 in color. 



Reproduction, aside from vegetative cell division, by hormogones and 

 resting spores. 



