LYNGBYA. 221 



of the cell, but leaving a pellucid margin all around, sub- 

 sequently becoming globular and granular. Zoospores six 

 or eight in each cell. 



Conf. zonata Web et Morh. Conf. lucens Dillw. t. 47. 

 Conf. bicolor, E. B. t. 2288. Spharoplea crispa Berk. 

 Glean. Algse, t. 3. fig. 1. 



This species delights in pure and running water, it growing 

 luxuriantly in that of cascades and waterfalls. It is every- 

 where common throughout Great Britain. Considerable con- 

 fusion seems to have prevailed relative to this plant, several 

 observers having repeatedly described it under different names. 

 I have no doubt whatever of the correctness of the synonymes 

 quoted. The form of the cells in this species is somewhat pecu- 

 liar. They are not exactly cylindrical, but taper gradually 

 from each extremity towards the centre of the cell, the ex- 

 tremities, or angles of the cells appearing in consequence 

 prominent. 



Two varieties of it have presented themselves to me ; the 

 one at Snaresbrook, Essex, in great quantity ; this agree- 

 ing with the species proper in all, save the length of the 

 cells, which are generally two and a half or three times as 

 long as broad ; the other in a stream at Wood Green, near 

 Cheshunt, in which the cells are cylindrical, completely filled 

 with endochrome, and not one third so long as broad. This 

 may be distinct. 



2. LYNGBYA MURALIS Ag. 

 Plate LIX. Fig. 7. 



Char. Filaments of less diameter than those of Lyngbya 

 zonata, dark green, entangled. Cells very short, two or 

 three times broader than long. 



Hob. On the ground in all damp situations early in the 

 spring. 



This is a very distinct species, rendered interesting from 

 the peculiarity of its habitat. The diameter of the filaments 



