- 



ACOTYLEDONS. ALG^. Zygnemct. 79 



occasionally seen them laterally united. The species of the 

 second division have more the appearance of true Conferva, 

 they are scarcely gelatinous; but they have no true joints, and 

 their internal structure resembles the true Oscillatorice. 

 * Simple decumbent, surrounded by a Mucus (Oscillatoriae verae) . 



1 . O. nigra, filaments brownish green rigid straight collected 

 into a gelatinous mass throwing out on all sides of its circum- 

 ference numerous long rays. Ag. p. 103. Conferva fonti- 

 nalis, Lighlf.p.977. Dillw. t. 64. E. B. t. 2054? Con- 

 ferva confragosa, Lightf. p. 976 ? 



HAB. Under water by the sides of limpid springs or fountains, and on 

 the banks of rivers, Lightf. Frequent in wells, Hopk. 



Vaucher and Agardh describe several species of this family, besides 

 the following, most or all of which will probably prove natives of 

 Scotland . 



2. O. limosa, filaments blueish green rigid straight collected into 

 a gelatinous mass and throwing out on all sides of its circum- 

 ference numerous rather short rays. Conferva limosa, Dlllw. 

 t. 20. E. B. f.2053. Oscillatoria tennis, Ag. p. 105. 



HAB. Rivulets and ditches, frequent, Hopk. 



** Simple, decumbent, not surrounded by a Mucus (Confervoideae). 



3. O. muralis, filaments green somewhat rigid curved flexuose 

 thickish interwoven into a green stratum, ringslax. Ag.p t 108. 

 Conferva muralis, E. B. t. 1554. Dillw. I. 1. 



HAB. On damp walls, stones, and shady gravel walks, very common, 

 Hopk. Walls of Branksome castle, Mr. Turner and Hook. 

 *** Erect, simple. 



4. O. scopulorum, filaments green curved flexuose erect minute 

 acuminate forming a dense velvet-like substance. Ag. p. \ \ 1 . 

 Conferva scopulorum, Dillw. Conf. Si/n. p. 39. T. A. E. B. 



f.2171. 



HAB. Rocks by the sea-side at Cawsie, Morayshire, Mr. Borrer and 

 Hook. 



10. ZYGNEMA. 

 (Conjugate, Vauch.) 



Filaments, containing granules which vary in their arrangement, 

 but take some decided figure, at length, from different filaments, 

 uniting by means of lateral titles. Filaments simple, equal, 

 jointed, green, gelatinous. Articulations pellucid. Granules 

 disposed either in spiral lines, in stellated figures, or, rarely, 

 scattered. Joints as in the true Confervce. The transverse 

 tubes are prolonged from the middle of the articulations of 

 two contiguous filaments at the same time, unite into one, are 

 pervious, and transmit the granules from one" articulation into 

 that of another filament, where they form an elliptical or sphae- 

 rical mass. 



