216 MONOCYSTE^. 



merata ( C. Brownii) arise from the sub-immersed habitat in 

 which it grows. Mr. Harvey thus describes C. Brownii : 

 " This forms exceedingly dense, very rigid tufts, of a black 

 green colour when growing, but on having the water 

 expressed, and being held to the light, exhibits a beautiful 

 yellow-green tint. Filaments so matted together, that it is 

 difficult to separate a single thread. They appear to ori- 

 ginate in a mass of creeping, branched, densely matted fibres, 

 which form the base of the tufts. They are erect, from half- 

 an inch to an inch high, flexuous, very rigid and elastic ; the 

 branches few and nearly simple, almost always secund, very 

 erect. A very curious and distinct plant, having, to the 

 naked eye, a good deal the appearance of Vaucheria terrestris, 

 but totally different in structure. It is perhaps allied to (7. 

 cegagropila. I have examined a specimen from Mr. Brown in 

 the late Mr. Templeton's herbarium, and find it to agree in 

 every respect with my Wicklow plant." 



2, CLADOPHORA CRISP ATA. 

 Plate LV. Figs. 1, 2. 



Char. Filaments very tenacious and of variable diameter, 

 crisped, and entangled. 



C. nigricans Dillw. Conf. Syn. 1. c. ; Harv. I. c. p. 356. 

 C. crispata Sm. E. Bot. t. 2350 ; Harv. 1. c. p. 356. 

 C. flavescens Harv. 1. c. p. 356. ; E. Bot. t. 2088. ; 

 Wyatt, Alg. Darm. No. 224. C. fracta Dillw. Conf. 

 t. 14. ; E. Bot. t. 2338. ; Harv. 1. c. p. 356. Micro- 

 spora Hass. in Annals, vol. xi. 



Hob. Everywhere common. Yar. nigricans in a pond at 

 Wimbledon, Surrey : Mr. Dickson. 



Three British species of Conferva appear all referrible to 

 this one : these are C. nigricans, C. fracta, and C. fiavescens. 

 C. Jlavescens I take to be the young state of C. crispata, 

 while C. fracta is assuredly the mature or perfect condition 

 of the plant : it is also equally certain that the C. nigricans 

 of Dickson is merely a discoloured state of C. crispata. 



