CONFERVACE^E. 141 



v 



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 Casparyi 

 X 200 diam. 



Rhizoclonium flavicans. Jury. Alg. 



Threads soft, simple, extremely fine, matted, somewhat 

 crisped, at first uniform pale green, at length distinctly jointed ; 

 articulations once and a-half as long as broad, dotted ; 

 interstices pellucid. 



SIZE. Threads '018 mm. diam. 



Eabh. Alg. Eur. iii., 331. 



Conferva arenicola, Berk. Glean, t. 13, f. 3. 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. 3 ' 

 Berkeley. 



Plate LIV. jig. 8. Portions of threads of Eliizocloninm 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 arrange- 

 ment of the species from Kabenhorst's Algae 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, 

 t Fruiting cells not terminal. 



* Cell- membrane even fracta. 



** Cell-membrane plicato-striate . . crisjjata. 



