THE GREEN ALGAE OF NORTH AMERICA 43 



trum acuminatum Lagerheiin, 1882, p. 71, PI. Ill, figs. 27-30; 

 W. & N., No. 441. Colonies of 4 cells ; cells somewhat lunate, 

 falcate or sigmoid, apices acuminate ; not in one plane, but as a 

 more or less curved surface, a median section of the colony 

 sometimes showing a curvature of as much as 180 ; cells 6-7 /* 

 thick, apices distant 30-40 /x. Wis., G. M. Smith. Europe. 



Smith (in litt.) states that his plant referred to above is certainly 

 a Scenedesmus, and to be identified with the plant of Lagerheim 

 and Chodat ; that he has also a true Selenastrum considerably 

 resembling it. If the same two species occur in Europe, it may 

 account for some recent authors doubting the validity of Chodat's 

 transfer of Lagerheim 's species. 



Var. MINOR G. M. Smith, I9i6a, p. 436, PI. XXIX, figs. 70-74. 

 Cells 3.5-6 //. thick, apices distant 18-28 /*. Wis., G. M. Smith. 



Var. TETRADESMOIDES G. M. Smith, 19163, p. 439, PI. XXIX, 

 figs. 75-80. Cells less lunate, 11-15 X 2.5-4 /*, curvature of 

 colony from slight to nearly a circle. Wis., G. M. Smith. 



5. S. INCRASSATULUS Bohlill, 1897, p. 24, PI. I, figs. 45-51 ', 



G. M. Smith, 19163, p. 440, PI. XXV, figs. 9-10. Colonies 4-8- 

 celled, occasionally 2-celled, cells in a single series or alternating, 

 or somewhat irregular, 17-24 X 5-8 /*; fusiform, subacute with 

 an apical thickening of the membrane, median cells usually 

 slightly curved, end cells distinctly so, outer side convex, inner 

 plane or concave. Stover's Pond, Harpswell, Maine, F. D. 

 Lambert. Brazil, Burma, 



In the Harpswell material the cells are irregularly placed, 

 showing little seriate arrangement, but otherwise are quite 

 typical. 



Var. MONONAE G. M. Smith, 19163, p. 440, PI. XXIX, figs. 

 81-83. Cells 11-12 X 4-4.5 M. Wis., G. M. Smith. 



Cells more slender than in the typical form, and smaller in all 

 dimensions. 



6. S. BIJUGA (Turp.) Lagerheim, 18933, p. 158 ; Collins, 

 1909, p. 168; G. M. Smith, 19163, p. 441, PI. XXV, fig. 2; 

 Achnanthes bij2iga Turpin, 1828, p. 310, PI. XIII, fig. 4. 



Vsr. FLEXUOSUS (Lemin.) Collins, 1909, p. 168 ; G. M. Smith, 

 19163, p. 446, PI. XXV, fig. 10 ; 5. bijugatus V3r. flexuosus 

 Lemmermann, iSgSb, p. 191, PI. V, fig. i. 



V3r. AI/TERNANS (Reinsch) Borge, 1907, p. 57; Collins, 1909, 

 p. 168; G. M. Smith, 19163, p. 447, PI. XXV, figs. 14-15 ; S. 

 alternans Reinsch, 1866, p. 135, PI. XX, fig. D. 5. 



