196 CONFERVACE^E. 



3. V. velutina, Ag. ; filaments creeping ; branches fastigi- 

 ate, woven into a velvety stratum ; sporangia solitary, globose, 

 lateral. Carm. Hook. 1. c. p. 319. 



On the muddy sea-shore, flooded by the tide. Annual. Spring and sum- 

 mer. Appin, Capt. Carmichael. Miltowu Malbay. " Filaments exceed- 

 ingly tough, interwoven into a dense, velvety, green stratum, pellucid 

 below and creeping over the mud ; branches near the extremity erect, fas- 

 tigiate, and more or less crooked. Vesicles solitary, globular, on short 

 lateral peduncles." Carm. 



ORDER XV. CONFERVACE.E. 



Conferveae, J. Ag. Alg. Medit. p. 12. Harv. Man. Ed. I, 

 p. 124. Lindl. Veg. Kingd. p. 18. Confervoideae, Endl. 

 3rd Suppl. p. 14. 



DIAGNOSIS. Green, marine or fresh-water Algse, composed 

 of articulated threads or filaments, simple or branched, free 

 or surrounded by gelatine. Cells cylindrical, truncated. 



NATURAL CHARACTER. Root rarely more than a point of 

 attachment, and often perishing on the maturity of the frond. 

 Frond in all cases composed of cylindrical, truncated cells 

 of moderate length, strung together in filaments, of which 

 they are the articulations. These filaments sometimes anas- 

 tomose, so as to form a net (as in Hydrodictyon] ; some- 

 times at maturity two separate filaments approach each other, 

 when a species of anastomosis takes place between them, a 

 cell in one filament becoming connected to a cell in another 

 filament by means of a membranous tube, through which the 

 contents of one are discharged either into the other, or else 

 lodged in the connecting tube ; in both cases forming the 

 nucleus of the fructification. This mode of connexion, 

 which is called conjugation, is characteristic of the sub-order 

 Zygnemea. In most cases, however, and in all the genuine 

 Confervea, the filaments are free one from another, either 

 simple or variously branched ; the ramification is frequently 

 alternate, or secund, rarely dichotomous, and rarely opposite. 

 In the sub-order Chtetophorete each frond consists of several 

 filaments combined together in a more or less perfect manner 

 by surrounding gelatine, and frequently terminating in hair- 

 like cellules of extraordinary length and tenuity ; whilst in 

 other species of this sub-order each cell is furnished with a 

 very long rigid seta, and this is remarkably obvious in Ochlo- 

 chcete, the only one of this sub-order which our limits admit. 



