MlCROSPORA 175 



made out at that early time in a form much finer than ours, 

 though it is quite possible that Agardh collected several different 

 forms as Conferva floccosa, just as any beginner now using 

 DeToni's Sylloge for authority would do. 



When we come down to the middle of the nineteenth century, 

 we can gain a somewhat more definite idea of Thuret's idea of the 

 species. Unfortunately, to be sure, no data as to diameter and 

 length of the cells are furnished ; but there are beautiful figures, 

 and from the magnification given with them, it may be estimated 

 that Thuret's type was practically the same as our specimens in 

 respect of size (*". e., 13-16//). 



To sum up : concerning the character of Vaucher's Prolifera 

 floccosa practically nothing can be determined ; of Agardh's Con- 

 ferva floccosa, we may be reasonably sure that it belongs in the 

 genus Microspora, and very likely it included our species ; finally, 

 there is no good reason to doubt that Thuret's Microspora 

 floccosa is the same as our species. At all events we cannot prove 

 that this conception, which has been adopted by several modern 

 algologists, is not historically correct. 



The uncertainty of the determinations of exsiccatae, or per- 

 haps their mixed character, is exemplified in the fact that at least 

 three numbers issued as Microspora floccosa, namely, Rabenh. 

 Alg. Sachs. J56, Aresch. Alg. Scand. 277, and Tild. Am. Alg. 

 139A, certainly contain M. amoena, a much larger species than 

 any form of M. floccosa. The specimen issued by Miss Tilden, 

 Am. Alg. ijpB, seems not much different from the smaller form 

 of the European authors and is at least very nearly allied to our 

 M. tumidula. 



In Microspora floccosa, Rabenh. Alg. Eur. 1985, which is 

 partly referred to Conferva abbreviata (Rabenh.) Wille by the lat- 

 ter author, we have been able to find only a form corresponding 

 to our definition of M. floccosa. 



6. Microspora Willeana Lagerheim ; DeToni, Syll. Alg. 1 : 

 228. 1887; Flora, 72: 207.pl. 5. fl i-icj. 1889 



Vegetative cells cylindrical, 11-14// in diameter, J^-i j£ 

 (rarely 2) times as long : chromatophore variable, but often more 

 dense and containing a larger amount of starch than in M. floccosa ; 

 cell-wall thin ; akinetes 14-16. 5 fi in diameter (/>/. 24, f 5-7). 



