OSCILLATORIA. 247 



fontinalis, t. 64. ; but the figure is more like O nigra. In 

 drying it adheres closely to paper. From O. major it differs 

 in the much greater diameter of its filaments, and darker 

 colour. It is therefore intermediate between these species. 



2. OSCILLATORIA MUCOSA Hass. 



Plate LXXI. Fig. 1. 



Char. Stratum gelatinous, dark, <eruginous green, glossy. 

 Filaments large. Striae subdistant. 



Hob. Floating in a pond like a little dusky cloud ; 

 Stevenston : Rev. D. Landsborough. 



This species agrees with the previous one in all its characters, 

 save in the arrangement of the striae. The filaments are of 

 the same diameter, of the same gelatinous habit, and present 

 the irregular and furrowed appearance when dried of O. 

 limosa : the only difference between the two species is in the 

 striae, which are twice as distant in this as in O. limosa. 



The only specimen which I have seen of this species is 

 that sent me by the Rev. D. Landsborough. There can be 

 no doubt entertained of its distinctness. 



3. OSCILLATORIA CINEREA Hass. 

 Plate LXX. Fig. 4. 



Char. Stratum of a dull ceruginous green colour. Filaments 

 large. Striae close, very evident. 



Hob. In a pond on Stanstead Common, Essex. 



This is a fine and well-marked species. The diameter of 

 the filaments is equal to that of the two preceding Oscilla- 

 torice, but they are infinitely less mucous, and the stratum 

 when dried is not in the least glossy, neither do the filaments 

 collapse or become wrinkled in drying, but preserve the same 

 equal diameter in the dried as in the recent state. The 

 species, judging from Carmichael's description, seems to 

 come near to the Oscillatoria littoralis of that observer. 



R 4 



