MICROSPORA 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 Comferva 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 (7. e., 13-16 p). 
To sum up: concerning the character of Vaucher's Prolifera 
Hoccosa practically nothing can be determined; of Agardh's Coz- 
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 Jrospora 
ffoccosa 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. 356, Aresch. Alg. Scand. 277, and Tild. Am. Ale, 
1394, certainly contain M. amoena, a much larger species than 
any form of 17 floccosa. The specimen issued by Miss Tilden, 
Am. Alg. 739B, 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. ۰ 
6. MicRosPoRA WILLEANA Lagerheim; DeToni, Syll. Alg. 1: 
228. 1887; Flora, 72: 207. pl. 5. f. 1-19. 1889 
Vegetative cells cylindrical, 11-14 م‎ in diameter, %-1% 
(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 nm diameter م)‎ 24, f. 5-7). 
