CONFERVACES. 141 
which sometimes consists of but a few empty cells, at other times 
lengthens out into a branch, Cells in the same fleece very various, and 
even in the same filament at different ages ; the full-grown cell seems to 
be fully six times as long as its diameter; but short cells once and 
a-half to twice as long as broad, which seem to be cells in process of 
development, are commonly mixed with the long cells. All contain a 
granular endochrome, the grains of very unequal size.’— Harvey. 
Plate LIV. fig. 7. Portions of thread of Rhizoclonium Casparyt 
X 200 diam. 
Rhizoclonium flavicans. Jurg. Alg. 
Threads soft, simple, extremely fine, matted, somewhat 
crisped, at first nniform pale green, at length distinctly jointed ; 
articulations once and a-half as long as broad, dotted; 
interstices pellucid. 
Size. Threads :018 mm. diam. 
Rabh. Alg. Eur. iii., 331. 
Conferva arenicola, Berk. Glean, t. 13, f. 8. Harv. Man. 
128. Harv. Phyc. Britt., t. 354 A. 
At the mouths of rivers, and salt marshes. 
“ Creeping on the sandy margin of pools in a salt marsh periodically 
flooded, forming a thin, soft, delicate, crisped web of a pale yellow green. 
Threads extremely slender, flexuous, at first self-coloured, with a few 
scattered dots, then with manifest dissepiments, and finally the granules 
contract and form a distinctly defined mass of a darker green in the 
centre, with pellucid interstices. Articulations one and a half times as long 
as broad. When dry the articulations are alternately contracted.”— 
Berkeley. 
Plate LIV. fig. 8. Portions of threads of Rhizocloninm flavicans 
X 200 diam. 
GENUS 62. CLADOPHORA. Kutz. (1843.) 
Articulate thread variously branched, cell-membrane usually 
thick, lamellose; cell contents parietal. 
Propagation by zoogonidia, arising from simultaneous and 
multipartite division of the cell contents, moving actively 
within the mother-cell, afterwards escaping by a lateral or 
terminal opening, furnished with 2 or 4 vibratile cilia, after- 
wards germinating without fecundation. 
Many species are entirely marine, but some are fresh water. All are 
disposed to considerable variation, and numerous varieties are named in 
connection with each of the fresh water species. The following arranges 
ment of the species from Rabenhorst’s Algz will be useful in their identi- 
fication :— 
I. Threads collected in tufts, more or less lax or intricate. 
A. Tufts at first attached, afterwards free swimming, 
a. Cell contents not spirally disposed, 
+ Fruiting cells not terminal. 
* Cell-membrane even . ... . © fracta. 
** Cell-membrane plicato-striate . . crispata. 
