ACOTYLEDONS. — ALG^. Zygiiema. 79 



occasionally seen them laterally united. The species of the 

 second division have more the appearance of true Confervce^ 

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

 their internal structure resembles the true Oscillatorice. 

 * Simple decumbent, surrounded by a Mucus (Oscillatorige 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. Jg. p. 103. Conferva fonti- 

 nalis, Lightf. p. dll . Dilliv. t. ()4. 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. limo^a, 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, Dillw. 

 t. 20. E. B. /.2053. Oscillaioria tenuis, Jg. p. 105. 



Ha3. Rivulets and ditches, frequent, Hopk. 



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



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



thickishinterwovenintoa green stratum, ringslax. y'Jg.p. 108. 



Conferva muralis, E. B. t. 1554. DiUiv. I. 7. 

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



Hopk. ^Vulls of Branksome castle, Mr. Turner and Hook. 

 *** Erect, simple. 

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



acuminate forming a dense velvet-like substance, ylg. p. 111. 



Conferva scopiduruni, Dilhv. Conf.Syn.p.'Sd. T. A. E.B. 



i.2l7l. 



Hab. Rocks by the sea-side at Cawsie, Morayshire, Mr. Dorrer and 

 Hook. 



10. Z\'GNEMA. 

 {Conjugata, T'auch.) 



Filaniejits, coutcuu'mf; granules which vary in their arrangement, 

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

 uniting by means of lateral lubes. — Filaments simple, ecpial, 

 jointed, green, gelatinous, ylrliculalions 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 eliij)tical or sph:«- 

 rical mass. 



