Oscillatoriea.l oscillatoria. 353 



have beautiful specimens of it from our excellent friend 

 Professor Scouler^ of Dublin. 



OSCILLATOEIA, Fauc/ier. 



Geu. Char. Filaments simple, even, clustered closely, striated, 

 and generally lying in a mucous matrix. — The name is from a 

 Latin word signifying to oscillate like the pendulum of a clock, 

 from the motion that the filaments are thought to make. 



1. Oscillatoria limosa, Fmic/ier. 



Hab. Ditches and sewers by road-sides. Common. 



Stratum rich dark green, very thin, gelatinous, with short 

 rays ; filaments pale green, straight ; striae rather distinct, 

 evident. 



It is not easy to determine the species in this genus ; 

 even in this one there is uncertainty. It is 0. tenuis of 

 Hassall, and 0. viridis of Johnston. The family, however, 

 of the OscillatonecE is one of the most distinct and remark- 

 able of the divisions of the Algae. They are distinguished 

 by the rapidity of their growth, the brilliancy of tlieir 

 colours, and the peculiar motion or oscillation of their 

 filaments, on which their generic name is founded. Mr. 

 Hassall does not think that there is anything very remark- 



2 a 



