(ECISTINA. 



[ 468 ] 



(EDOGONIUM. 



an entire margin; body attached to the bot- 

 tom of a fixed cyhndrical carapace; eyes 

 two, frontal, red, disappearing in advanced 

 age. 



O. crystallinus (PI. 35. fig. 16). Carapace 

 hyaline, viscid, covered with foreign bodies ; 

 aquatic; entire length 1-36". 



Jaws each with three teeth. 



BiBL. Ehrenberg, Infus. p. 392. 



CECISTINA, Ehr.— A family of Rotatoria. 



Char. Animals single or aggregate, at- 

 tached to the bottom of a gelatinous cara- 

 pace ; rotatory organ single, with an entire 

 margin. 



A distinct carapace for each animal l.fEcistes, 



Carapaces aggregated into a sphere 2.Conochilus. 



BiBL. Ehrenberg, Infus. p. 391. 



CEDEMIUM, Fr.— A genus of Dematiei 

 (Hyphomycetous Fungi). (E. atrum, Corda, 

 consists of dense tufts of brown erect fibres, 

 scarcely branched, and without true septa. 

 The roundish "spores" are sessile upon the 

 sides of the erect filaments. 



BiBL. Corda, Sturm's Deutschl. Fl. 6. 

 pi. 9 ; Fries, Systema Myc. 344 ; Berkeley 

 and Broome, Ann. Nat. Hist. 2 ser. vi. p. 466. 



CEDIPODIUM, Schwagr.— A genus of 

 Splachnaceae (Acrocarpous, operculated 

 Mosses), sometimes included under Gymno- 

 stomum. (Edipodium Griffithianum, Schwag., 

 the only species, is remarkable for the pecu- 

 liarly thickened fruit-stalk, whence the name 

 of the genus is derived. 



(EDOGONIUM,Link.(ProZ?/era,Leclerc, 

 Vesiculifera, Hass). — A genus of Conferva- 

 cese (Confervoid Algae), which, from their 

 peculiar mode of growth and reproduction, 

 ought perhaps to form a distinct family. 

 Some of the (Edogonia are among the com- 

 monest and most abundant of freshwater 

 Algae, occurring in every pond, ditch, or 

 stream, and quickly making their appearance 

 in tanks, aquaria, &c. They may generally 

 be recognized at a glance by the dense and 

 uniform green protoplasm, sometimes filling 

 the cells, sometimes (after dividing) leaving 

 half of the cell colourless and devoid of 

 chloroi)hyll ; above all, by the annular stria? 

 occurring at the ends of many of the cells 

 (PI. 5. fig. 7 b, h). The cells have each a 

 large parietal nucleus (fig. 7 «)• The large 

 round interstitial sporangial cell (fig. 7 g) is 

 also a very distinctive character. The zoo- 

 spores also are peculiar, consisting of the 

 entire contents of a cell, therefore very large, 

 and are crowned by a wreath of cilia (PI. 5. 

 fig. 7 c). The filaments are attached, when 

 young, to stones, plants, &c., by root-like 



processes. These plants, on many grounds, 

 desei-ve a somewhat close examination. The 

 filaments are composed of rows of cylindrical 

 cells, which multiply interstitially in a very 

 curious manner. When a cell divides, the 

 division of the primordial utricle first takes 

 place (this division must be looked for in 

 cells densely filled with contents), and two 

 new cells are formed within the parent. At 

 the same time an annular deposit of cellulose 

 occurs around the upper part of the parent- 

 cell. Next the wall of the parent-cell breaks, 

 by a circumscissile dehiscence, just below 

 the cellulose ring. The new cells elongate 

 and remove the margins of the circular slit 

 from each other, the upper piece of the 

 parent-cell wall being pushed up as a kind 

 of cap on the uppermost of the new cells. 

 This is pushed up further and further by the 

 elongation of the lower cell, until the upper 

 end of the latter comes above the line of 

 dehiscence. The annular deposit of gela- 

 tinous cellulose has meanwhile become 

 stretched or developed over the space left 

 by the separation of the halves of the parent 

 membrane, forming an outer coat to the new 

 cell. After the growth of the lower cell is 

 finished, the upper one begins to elongate, 

 until it attains equal length ; it remains poor 

 in protoplasm and chlorophyll while grow- 

 ing, but becomes densely filled when it has 

 attained its full dimensions. The margins or 

 broken ends of the parent-cell wall form the 

 annular striae seen on the filaments (PL 5. 

 fig. 7 b, g, h) ; at first there is only one at 

 the top of any given cell, but the next dehis- 

 cence takes place just below this, giving 

 rise to a second, and so on, until many suc- 

 cessive rings are produced at one spot. 



The zoospores or ciliated gonidia (fig. 7 c) 

 are formed from the entire contents of a 

 cell, and exhibit a large round nucleus ; they 

 escape by a circumscissile dehiscence of the 

 wall of the parent-cell [b) ; the filament, 

 however, does not generally become quite 

 brokeninto two; theportions remain attached 

 by a strip of the side-wall forming a kind of 

 hinge. The zoospores are large, somewhat 

 ovate in form, with a transparent region at 

 one end, whence the numerous cilia arise. 

 When expelled, they move for a time, and 

 then come to rest, attaching themselves to 

 foreign objects by the ciliated end, acquiring 

 a membrane, sending out root-like processes 

 below (e), and elongating and expanding 

 above into a longish pear-shaped body. 

 Sometimes the zoospores do not completely 

 extricate themselves from the parent-cell. 



