]38 WISCONSIN PHYTOPLANKTON 



KEY TO THE SPECIES. 



Ends of cells rounded Q. PFITZERI 



Ends of cells pointed. 



Chloroplast notched at the center Q. CHODATI 



Chloroplast not notched at the center Q. LACUSTBIS 



Quadrigula Pfitzeri (Schroder) comb. nov. PI. 33, Figs. 1-2. 



Rhaphidium Pfitzeri Schroder, Verh. d. Nat.-Med. Ver. zu Heidelberg N. F. 

 7: 152, pi. 6, fig. 6. 1902. 



Ankistrodesmus Pfitzeri (Schrode-) G. S. West, Brit. Freshw. Algae 224, 

 figs. 94G-34H. 1904. 



Cells about 7 times as long as broad, central portion cylindrical with 

 ends slightly tapering and rounded. Chloroplast generally filling the 

 entire cell, with or without a pyrenoid. (Euplanktont). 



Breadth of cells 3-6 p., length 22--4S (generally about 35) /*. 



Bear (1) (IT), Beaverdam (rr), Blake (IT), Chain (rr), Clear (rr), 

 Cochrane (sss), Devils (1) (s), Fishtrap (rrr), Found (r), Fowler (rr), 

 Harris (rr), Hillman (ss), Jennie (rr), Lac Court Oreilles (rr), Lindy (rr), 

 Long (2) (rrr), Little Wood (rr), Mud (1) (rr), Mudhen (rr), Oconomowoc 

 (rr), Okauchee (rr), Palmer (sss), Pardee (rr), Pine Tree (r), Poplar (r), 

 Reserve (rr), Rice (1) (rr), Sand (1) (rr), Shell (rr), Sishebogema (rr), 

 Travis (rr), White Ash (r), Whiteflsh (rr), Wild Goose (rrr). 



The chief characteristic of the genus is the arrangement of the cells 

 in groups of 2-4-8 with their long axes parallel to the long axis of the 

 colony, together with the gelatinous envelope that surrounds the colony. 

 Admitting the generic validity of Quadrigula, Ankistrodesmus Chodati 

 and A. lacustris are in a much more natural position when placed with 

 Quadrigula species. 



Quadrigula Chodati (Tanner-Fullman) comb. nov. PI. 33, Fig. 3. 



Raphidium Chodati Tanner-Fullman, Bull. Herb. Boiss. 2 Ser. 6: 156, figs. 

 1-11. 1906. 



Ankistrodesmus Chodati (Tanner-Fullman) Brunnthaler, in Pascher, Siiss- 

 wasserfl. Deutschl., osterr. u. d. Schw. 5 2 : 193, fig. 306. 1915. 



Cells linear, arcuate, or lunate ; fusiform and tapering to sharp ends. 

 Longitudinally arranged in a gelatinous colony of 4-8-16 or more cells. 

 Cells with a single, parietal, laminate chloroplast that is notched at 

 the center and contains two pyrenoids. (Euplanktont). 



Breadth of cells 3.5-7 /*, length 30-80 ^ Colonies up to 50x250 M . 



Boulder (r), Little Bass (2) (rrr), Lac du Flambeau (rr), Sand (3) (ss). 



Tanner-Fullman states that the cells are always lunate but those that 

 I have observed were always straight or slightly curved. The notching 

 of the chloroplast together with the two pyrenoids is such a distinct 



