310 Prof. Decandolle on a New Species of Oscillator ia. 



almost all irregular and slashed at the margin. On one side they 

 are whitish, and on the other of a dirty green, from half an 

 inch to three inches long, and from half an inch to an inch 

 wide. Under the microscope they show no distinct trace of 

 organization. It is possible that they may be the debris of large 

 vegetables which live in the lake, such as the Nenuphars and 

 Scirpes. It is possible that they may be substances analogous 

 to some species of ulva or rivalia half decomposed ; or it is 

 possible that they may be the debris of the skins of the oscilla- 

 toria^ and be analogous to the body which Professor Vaucher 

 has figured in his oscillatoria vaginata, and in all the Nostochs. 

 If this last hypothesis is verified, it will tend to confirm the 

 idea that the oscillatoria of Morat is different from the oscilla- 

 toria mbfusca. 



When the oscillatoria of Morat are placed in water, they ar- 

 range themselves on the margin of the vessel in long filaments, 

 of a colour which is brown in their lower part, and green in the 

 upper part. Does this green part form an integral part of the 

 other ? Is it the beginning of the formation of a skin ? Is it 

 a particular age of the oscillatoria ? or is it a formation foreign 

 to its essence ? All these questions have not yet been com- 

 pletely answered. Analogy with the other species of the ge- 

 nus seems to confirm the opinion, that this green production 

 actually makes a part of the developement of the oscillatoria, 

 and is perhaps the commencement of the formation of a skin. 



This new animal may be described as follows, in the lan- 

 guage of natural history : — 



Oscillatoria rubescens. 



0. fjlis cylindricis tenuissimis ( y J 5 lin. diam.) fusco-ru- 

 bescentibus, confertissime annulatis. 



Conferva purpurea aquis innatans. — Haller, Helv. No. 

 2109? 



Hab. in Lacu Morattensi ; precipue hyeme et vere ; inter- 

 dum temperie favente valde multiplicata ad superficiem flui- 

 tans, et aquam rubram efficiens. 



The gentlemen who undertook the chemical examination of 

 the substances above described, found that the red matter was 

 composed of 



1, A resinous red colouring matter. 



