44 WISCONSIN PHYTOPLANKTON 



KEY TO THE SPECIES. 



Colonies endophytic in gelatinous envelope of other algae. . 



A. NiDtrLANS v. ENDOPHTTICA 



Colonies not endophytic. 



Cell contents grey to pale blue-green, never bright blue-green. 



Colonies ovoid to spherical, never perforate A. NIDULANS 



Colonies reticulate to clathrate A. CLATHBATA 



Cell contents bright blue-green. 



Cells less than 5 M broad A. STAGNINA 



Cells more than 5 M broad A. PBASINA 



APHANOTHECE CLATHRATA W. & G. S. West. PL 6, Fig. 3. 

 Trans. Roy. Irish Acad. 32, Sec. B: 111, pi. 10, figs. 9-11. 1906. 



Colonies microscopic ; free-floating ; elongate and irregular in shape, 

 usually perforate and reticulate. Gelatinous colonial envelope hyaline 

 and homogeneous. Cells very small, bacilliform, straight or curved, 

 embedded in a solid mass in the colonial envelope. Cell contents homo- 

 geneous, grey to light blue-green. (Euplanktont). 



Cells 0.6-1.0 p. broad, 3.5-4.5 p. long. 



Lindy (r), Little Crooked (sss), Nancy (ss), Pokegama (1) (r), Poor 

 Farm (rr), iSand (1) (ss), Wolf (ss). 



APHANOTHECE NIDULANS P. Richter. PI. 6, Fig. 1. 



Bot. Not. 1884: 128. 1884. 



Colonies spherical, ovoid, or ' ' nest-shaped ' ' ; enclosed by a homogene- 

 ous, hyaline, gelatinous envelope. Cells broadly cylindrical, straight 

 or curved, of small size and fairly close together. Individual sheaths 

 of cells confluent with the colonial envelope. Cell contents homogene- 

 ous, grey to light blue-green. (Facultative Planktont). 



Cells 1.0-1.5 p. broad, up to 3.5 p. long. 



Beaver (2) (ss), Deer (ss), Lower McKenzie (sss), Pokegama (sss), Ten- 

 derfoot (r). 



Certain species of this genus resemble bacterial colonies in much the 

 same manner as the minute-celled species of Aphanocapsa. Here again 

 the color of the cell contents is good evidence of the algal nature of the 

 organism. 



var. ENDOPHYTICA W. & G. S. West. PI. 5, Fig. 6. 

 Jour. Linn. Soc. Bot. 40: 432, pi. 19, fig. 14. 1912. 



Cells embedded in gelatinous envelope of other colonial Myxophy- 

 ceae. Gelatinous envelope of colony confluent with envelope of host 



