754 



THE AMEBIC AN NATURALIST 



[Vol. XLIX 



location and character of the pools, nevertheless some 

 forms appeared constantly. Among the filamentous algae, 

 Spirogyra was almost uniformly present, appearing 

 twenty-eight times out of thirty. The species were not 

 identified until March, but in the twenty collections taken 

 in the spring and early summer, the most frequent species 

 was Spirogyra varians. Spirogyra insignis was found 

 five times. Other species seen less frequently were : 

 8. tenuissima S. communis 



S. sticticum S. fluviatilis 



S. grevilliana S. bellis 



S. weberi S. nitida 



S. quinina S. inflata 



S. crassa S. decimina 



S. majuscula S. rivularis 



Usually the masses contained several species of Spiro- 

 gyra, often with a large proportion of one species, and the 

 Spirogyra was almost invariably associated with other 

 filamentous algae. Among the most frequent of these 

 were Mougeotia and Zygnema. Vaucheria was found 

 frequently in the autumn and early winter. Oscillatoria 

 was quite constant after its first occurrence in early 

 March, but it was usually in very small quantities. Ulo- 

 thrix Draparnaldia and Microspora were seen occasion- 

 ally, but not in abundance, while Anaboena oscillaroides 

 was found only once. In general, the large permanent 

 pools produced the greatest variety of genera and species 

 of these algae, but otherwise there was no apparent rela- 

 tion between the genera of algae produced and the char- 

 acter and location of the pools ; with the possible excep- 

 tion of Draparnaldia plumosa, which was found four 

 times out of five in shallow ditches. 



Diatoms, Desmids and Other Algce.— Diatoms were in- 

 variably present. Of these, there were four that were 

 constant and always in greater quantity than other kinds. 

 These four were Navicula, in great variety, Synedra, Coc- 

 conema and Gomphonema. Other diatoms were seen ir- 



