WISCONSIN PETTOPLANKTON 75 



DINOBRYON DIVERGENS Imhof . PI. 14, Fig. 2. 



Jahresbr. d. Naturf. Ges. Graub lindens N. F. 80: 134. 1887. 



Dinobryon cylindricum,va,r. divergens (Imhof) Lemmermann, Ber. d. D. Bot. 

 Ges. 18: 517, pi. 19, figs. 15-20. 1900. 



Cells in free-floating densely or openly branched colonies. Recep- 

 tacles with conical bases and the upper portion cylindrical or with 

 slightly flaring mouths. The axis of the upper portion of receptacle 

 forming an angle of 45-90 degrees with that of the basal portion. Sides 

 of receptacle sometimes undulate. Seasonal variation confined to dense- 

 ness of branching in colony rather than changes in receptacle shape. 

 (Facultative Planktont). 



Eeceptacles 7-8 p. broad, 35-50 p long (20-27 /A in upper portion and 

 15-20 in basal portion). 



Beasley (s), Boulder (cc), Browns (cc), Center (ss), Devils (1) (ss), 

 Elizabeth (cc), George (r), Green (2) (rr), Hill (cc), Lac la Belle (ss), 

 Long (2) (rr), Marl (ss), Mary (cc), Meta (r), Mill (cc), Mud (1) (ss), 

 Nagawicka (cc), North Turtle (ss), Oconomowoc (cc), Otter (ss), Rock (ss), 

 Round (4) (rrr), Silver (2) (cc), Speese (cc), Tamarack (ss), Taylor (ss), 

 Tied Canoe (ss). 



HYALOBRYON Lauterborn 1896. 



Cells solitary or in branching colonies, free-floating or epiphytic. 

 Receptacle shape and cell contents as in Dinobryon but with the wall 

 of the receptacle containing a number of successive growth rings instead 

 of homogeneous. Wall of receptacle more delicate than Dinobryon. 



HYALOBRYON MUCICOLA (Lemmermann) Pascher. PI. 14, Figs. 3-4. 



D. iSiisswasserfl. Deutschl., osterr. u. d. Schw. 2, Flagellatae 2: 81, fig. 131. 1913. 

 Hyalobryon Lauterbornei var. mucicola Lemmermann, Ber. d. D. bot. Ges. 

 19: 340. 1901; Bachmann, Arch. f. Hydrob. u. Planktonkde. 8: 81, figs. XI 18 - 

 XI". 1908. 



Cells solitary, epiphytic upon gelatinous envelope of colonial Myxo- 

 phyceae, Chlorophyceae and Phaeophyceae. Receptacle delicate, upper 

 portion cylindrical and with a flaring mouth, lower portion conical and 

 with a short stipe. Growth rings of receptacle numerous. Protoplast 

 ovoid, attached to base of receptacle, with two golden-brown chromato- 

 phores, two cilia of unequal length and an eyespot. (Euplanktont). 



Receptacles 4-6 /* broad, 25-45 ^ long; stipe 4-12 p. long. 



Crawling Stone (r), Lac du Flambeau (sss), Long (3) (c), Mud (2) (rr), 

 Round (1) (rr). 



