Rhizoclonium Hookeri Kuetzing 1849, p. 383 



PI. 23, Figs. 4-7 



Filaments crisp, freely-branching, composed of long, cylindrical or 

 irregularly inflated cells, 60-64/x in diameter ( rarely up to 103fi ) and 

 6-7 times their diameter in length. Cells of the branches about the 

 same diameter as those of the main filament. Secondary branching 

 not uncommon. 



In hard water lakes and ponds; entangled about submerged aqua- 

 tics. Mich., Wis. 



BASICLADIA Hoffman & Tilden 1930, p. 380 



Thallus a coarse, erect, and attached filament with prostrate, rhi- 

 zoidal portions serving as anchoring organs, giving rise to the erect 

 filaments which branch near the base, but sparsely. Basal cells cylin- 

 drical, very long, becoming shorter and wider above. Walls thick and 

 lamellate. Chloroplast a thin, sometimes dense, parietal reticulum. 

 Sexual reproduction by isogametes produced in unmodified cells in 

 the distal region of the filament (Hamilton, 1948); asexual repro- 

 duction by zoospores possible also. 



This genus contains only 2 known species at present, both of 

 which are specifically epizoic on the backs of turtles although 

 they may occur on other hard surfaces also. The filaments are 

 often tightly compacted and entangled, making it difficult to ob- 

 serve the origin of branches and the exact relation of the rhizoidal 

 basal portions of the thallus to the erect filaments. 



Key to the Species 



Cells 12-20^ in diameter below, 35^ in diameter 



in the distal region — B.chelonum 



Cells 50/Lt in diameter below, 120^ in diameter 



in the distal region^ B. crassa 



Basicladia chelonum (Collins) Hoffmann & Tilden 1930, p. 382 



PI. 23, Figs. 8-12 



Frond a coarse, attached, erect filament; branching only at the 

 base, just above the attaching organs, which anchor the plant to the 

 backs of turtles (especially the snapping turtle, Chelijdra serpentina). 

 Main filament 12-20/i, in diameter below and up to 35/* in diameter 

 in the distal region. Cells cylindrical, especially the basal cells, which 

 may be as much as 50 times their diameter in length. Walls thick 

 and lamellate. 



On backs of snapping turtles; widely distributed. Mich., Wis. 



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