TUFTS COLLEGE STUDIES, Vol. IV, No. 7. 



THE GREEN ALGAE OF NORTH AMERICA, 



SECOND SUPPLEMENTARY PAPER. 



BY FRANK S. COU<INS. 



In the five years since the first supplement to the Green 

 Algae of North America, Vol. Ill, No. 2, of this series was 

 published, many species known from other countries have been 

 found to occur here, while to a larger extent than in the first 

 supplement, species and genera new to science have been dis- 

 covered here. The largest contributors to this increase have 

 been E. N. Transeau and G. M. Smith. Transeau's papers, 

 1913, 1914, 1915, beside a general account of the algae of the 

 prairie regions of Illinois, give a careful study of our Zygne- 

 maceae and Mesocarpaceae with many new species, and also 

 a number of new species of Ocdogonium. Transeau, 19133, is 

 a study of seasonal variation in algae, covering a period of five 

 years; Transeau, 1917, reports collections in Michigan in 1915. 

 G. M. Smith, 1916, igiGb, form a very important contribution 

 to the knowledge of our plankton forms, giving the results of 

 two years' exploration of the lakes of Wisconsin. Smith, 19163, 

 is a monograph of the genus Scencdesmus, intended to include 

 all references in print, and probably coming as near to com- 

 pleteness as is humanly possible. Smith, 1913, describes a new 

 and interesting genus ; other papers by the same author are of 

 special interest in other than systematic lines. It is a matter 

 for congratulation to all interested in the study of our fresh 

 water algae that two men whose names did not appear in the 

 original paper or its first supplement are now doing work equal 

 to the best anywhere. The species of Transeau and Smith 

 have been included here as given by them ; it is probable that, 

 as in all such cases, changes will later be found necessary, but 

 they cannot be foreseen. Borgesen, 1913, and Collins & Her- 

 vey, 1917, add a number of species from subtropical regions, 

 the former from the Danish West Indies,* the latter from Ber- 



* These islands have lately been purchased by the United States, and 

 in the following text will be referred to by their new name, the Virgin 

 Islands. 



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