THE GREEN ALGAE OK NORTH AMERICA 37 



22. Body of cell inconspicuous, rays twice bifid, total diam. up to 



7 V~ 22. T. limneticuin. 



22. Body more conspicuous, rays once bifid or trifid ; total diam. not 



over 33 /*. 28. T. hastatum. 



23. Cells irregularly octaedral. 25. T.floridense. 



23. Cells 3- or more-angled. 24. 



24. Cells flattened. 27. 



24. Cells not flattened. 25. 



25. Cells with rounded sides and inconspicuous angles. 



14. T. arinatum. 



25. Cells irregularly tetraedric, with conspicuous angles. 26. 



26. Angles and spines repeatedly forked. 16. T. enortne. 



26. Angles short, with concave ends and 2 short spines. 



15. T. b if urea turn. 



27. Cells quadrangular. 26. T. lobiilatuni var. polyfiircatum. 



27. Cells polygonal. 10. T, angulosum. 



28. Cells cruciate. 23. T. pusillum. 



28. Cells with 2 long, subparallel, and 2 deeply emarginate sides. 



29. T. artkrodesmiforme var. lobnlalum. 

 29. Cells much twisted, with deep median division into semicells. 



30. T. victoriae. 

 29. Cells without deep division, with 3 or 4 unequal sides. 



9. T. quadricuspidalum. 

 30. Width between apices 30-40 /x; cells flat or pyramidal. 



26. T. lobulatum. 

 30. Width between apices 50-70 M ; cells flat. 24. T. planctonicum. 



Page 162, after TETRAEDRON TRIGONUM var. PUNCTATUM, 

 add, 



Var. SETIGERUM (Archer) I/emmermann, 1904, p. no; Tetra- 

 pedia setigera Archer, 1872, p. 365, PI. XXI, figs. 14-17 ; G. S. 

 West, 1904, p. 349 ; Polyedrium trigonum var. setigerum 

 Schroder, 1898, p. 23, PI. I, fig. 6. Cells with strongly con- 

 cave sides, the rounded angles each with a long straight spine. 

 Wis., G. M. Smith. Europe. 



Described by Archer and accepted by West and Forti as be- 

 longing to the Myxophyceae, the species seems to belong 

 better to the Chlorophyceae, as surmised by Schroder and 

 Lemmermann ; as noted by G. M. Smith the chromatophore is 

 grass-green and contains a single central pyrenoid. Shape 

 and dimensions agree exactly with Archer's description, so that 

 there is little doubt of the identity. 



Page 165, after T. REGULARS var. LONGISPINUM, add, 



Var. INCUS Teiling, 1912, p. 277, fig. 12. Cells tetraedral, 



56097 



