CYATHEA. 



[ 223 ] 



OrCLAMMINA. 



Tropical or subtropical, mostly arbo- 

 rescent. 



Genera. 



Cyathea. Sori hemispherical, regularly 

 aiTanged. Indusium at first closed, at 

 length bursting in a circumscissile manner, 

 and cup-shaped. 



Ahophila. Sori globose, regularly ar- 

 ranged. Sporanges inserted on a globose 

 axis, and imbricated. 



Ilcmiti'Ua. 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 liard-membranaceous, en- 

 tire, finaUy bursting irregularly at the 

 summit ; capsules numerous, nearly sessile, 

 annulus broad. 



Mutonia. Keceptacle expanded into a firm 

 and membranaceous umbrella-shaped ob- 

 scurely 6-lobed indusium, enclosing 6 large 

 sessile capsules. 



Thyrsopteris. 



CYA'THEA, Smith.— A genus of Cya- 

 the88(Polypodiaceous Ferns), most of which 

 are tropical. They have a cup-like in- 

 dusium, whence the name. Arborescent. 

 (Figs. loO, 151.) 55 species. 



Fig. loO. 



Fig. 151. 



Cyathea elegans. 

 Fig. 150. Pinnule with sori. MagniBed 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 (PL 53. fig. 17). 



BiBL. Fromentel, Microzoaires ; Kent, 

 Inftis. 141. 



CY ATHUS, Hall.— See Xidulariacei. 



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- 

 NOSPKRMi.A..) Species of Cycas, Zar/iia, &c. 

 are commonly cultivated in botanical gar- 

 dens. Tliey 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. Tliis is ex- 

 tracted and used as arrowroot or sago. Cycas 

 circinalis furnishes a kind of sago (its starch- 

 grains are represented in PL 46. fig. 17). 

 Dion edule 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 hke those of Arau- 

 caria (with many rows of bordered pits) 

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

 exists, composed of unrollable 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 uuroUable 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, hoAvever, are 

 not " annual," only five or six existing in 

 large old trunks. The leaves of the Cyca- 

 dacese possess a remarkably solid epidermal 

 structure ; and in Cycas the upper thickened 

 walls of the epidermal ceUs exhibit pore- 

 canals or deep pits running from the cavity 

 of the cell towards the outer sm-face, as well 

 as towards the contiguous cells (PL 47. 

 fig. 28). See Epidermis. The pollen of 

 the Cycadaceae 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. Is. H. v. 48; Linn. 

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

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

 Icon. Select, fasc. ii. t. ix. & xv. ; Miquel, 

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

 Sc. Nat. 3 ser. v. 11). Also the Bibl. of 

 Gymno.spermia. 

 CY'CAS, L. See Cycadace.e. 

 CYCLAM;MINA, Brady.— An arena- 

 ceous Foraminifer ; nautiloid, subglobose, 

 with numerous chambers, lab\Tinthic with- 

 in ; last chamber opening with a transverse 



