CYATHEA. 



[ 223 ] 



CYCLAMMINA. 



Tropical or subtropical, mostly arbo- 

 rescent. 



Genera. 



Cyathea. Sori hemispherical, regularly 

 arranged. Indusium at first closed, at 

 length bursting in a circumscissile manner, 

 and cup-shaped. 



Alsophila. Sori globose, regularly ar- 

 ranged. Sporanges inserted on a globose 

 axis, and imbricated. 



Hem&eUa. Sori globose, each solitary 

 on a venule. Indusium an ovate, concave, 

 torn scale, situated at the lower side of the 

 base. 



Cnemidaria. 



Dicalpe. Receptacle small, scarcely ele- 

 vated. Indusium hard-membranaceous, en- 

 tire, finally bursting irregularly at the 

 summit ; capsules numerous, nearly sessile, 

 annulus broad. 



Matonia. Receptacle expanded into a firm 

 and membranaceous umbrella-shaped ob- 

 scurely 6-lobed indusium, enclosing 6 large 

 sessile capsules. 



Thyrsopteris. 



CYATHEA, Smith. A genus of Cya- 

 these (Polypodiaceous Ferns), most of which 

 are tropical. They have a cup-like in- 

 dusium, whence the name. Arborescent. 

 (Figs. 150, 151.) 55 species. 



Fig. 150. 



Fig. 151. 



Cyathea elegans. 



Fig. 150. Pinnule with sori. Magnified 5 diameters. 

 Fig. 151. Vertical section of a sorus in a cup-like in- 

 dusium. Magnified 25 diameters. 



BIBL. Hooker and Baker, Syn. Fil. 16. 



CYATHO'MONAS, From. = Monas 

 truncate or excavate in front. 



8 species; freshwater; length 1-3000 to 

 1-1000". C. spissa (PI. 53. fig. 17). 



BIBL. Fromentel, Microzoaires ; Kent, 

 Infm. 141. 



C Y ATHUS, Hall. See NIDULAKIACEI. 



CYCADA'CE^E. A family of Gymno- 



spermous Flowering Plants. The micro- 

 scopic structure of the wood is analogous to 

 that of the Conifers; and the mode of ferti- 

 lization of the ovules is similar. (See GYM- 

 NOSPEBMIA.) Species of Cycas, Zamia, &c. 

 are commonly cultivated in botanical gar- 

 dens. They offer interesting subjects of 

 microscopic investigation. The parenchy- 

 matous tissue, in the form of pith, large 

 medullary rays, and in Cycas of concentric 

 rings alternating with those of the wood, is 

 remarkable for the quantity of starch con- 

 tained in it at certain periods. This is ex- 

 tracted and used as arrowroot or sago. Cycas 

 circinalis furnishes a kind of sago (its starch- 

 grains are represented in PI. 46. fig. Vj\ 

 Dion edide yields a kind of arrowroot in 

 Mexico. Encephalartos yields Caffre-bread 

 at the Cape, &c. The wood is composed, 

 in Cycas and Zamia, almost wholly of large 

 dotted tubes, somewhat like those v of Araur 

 caria (with many rows of bordered pits) 

 (PL 48. fig. 20) ; but a medullary sheath 

 exists, composed of unreliable spiral vessels, 

 with tubes of varied character, reticulate, 

 annular or other fibrous forms, as in the 

 Dicotyledons; and in Zamia the dotted 

 tubes are said to be unreliable in some cases 

 into spiral ribands. In Zamia and Ence- 

 phalartos there does not appear to be a dis- 

 tinction of concentric rings of wood; but 

 in Cycas these exist, separated by layers of 

 cellular tissue. The rings, however, are 

 not " annual," only five or six existing in 

 large old trunks. The leaves of the Cyca- 

 daceae possess a remarkably solid epidermal 

 structure ; and in Cycas the upper thickened 

 walls of the epidermal cells exhibit pore- 

 canals or deep pits running from the cavity 

 of the cell towards the outer surface, as well 

 as towards the contiguous cells (PI. 47. 

 fig. 28). See EPIDERMIS. The pollen of 

 the Cycadaceee is angular, collected in 

 masses, and transparent ; it is contained in 

 anthers of peculiar form seated on the lower 

 surface of the scales of the male cones. 



BIBL. Don, Ann. N. H. v. 48; Linn. 

 Trans, xvii. ; Brongniart, Ann. Sc. Nat. 

 xvi. 589; Mohl, Verm. Schrift. 195; Link, 

 Icon. Select, f asc. ii. t. ix. & xv. ; Miquel, 

 Linncea, xviii. 125, and pis. 4, 5, 6 (Ann. 

 Sc. Nat. 3 sSr. v. 11). Also the BIBL. of 

 GYMNOSPERMIA. 



CY'CAS, L. See CYCADACEJE. 



CYCLAM'MINA, Brady. An arena- 

 ceous Foraminifer; nautiloid, subglobose. 

 with numerous chambers, labyrinthic with- 

 in ; last chamber opening with a transverse 



