MUSCI OR BRYACE^ — HEPATICjE. 643 



appear on newly-formed islands. In speaking of the morphology of 

 mosses, Lindley states that the calyptra may be considered as a con- 

 volute leaf, the operculum another, the peristome one or more whorls 

 of minute flat leaves, and the theca itself as the excavated distended 

 apex of the seta. In a specimen of Tortula fallax, which I received 

 from the late Mr. E. Quekett, leaves are produced at the top of the 

 seta in place of the spore-case. Dusting-brooms, called silk brooms, 

 are made in Sussex from Eolytricham commune. 



Mosses have be6n divided according as their sporangia are ter- 

 minal (acrocarpi, axgos, at the top, xa^mg, fruit), or on short 

 lateral branches {cladoca/rpi, xXddoe, a branch), or from the axil of 

 leaves (pleurocarpi, TXev^ov, side) ; according as the operculum is adhe- 

 rent or not ; and according as the mouth of the theca is naked, or has 

 a single or double peristome, aploperistomi (dirXoos, single), and diplo- 

 peristomi [bitrkoog, double). Divisions have also been adopted, founded 

 on the position of the antheridia and archegonia, etc. There are 3 

 sub-orders: — 1. Bryese, urn mosses; csespitose mosses, urn-shaped 

 sporangia, with calyptra, usually an operculum ; peristome with or 

 without teeth, central columella, no elaters. 2. Sphagnese, bog-mosses ; 

 aquatic plants, with spirally imbricated leaves, clustered branches, 

 spiral cells, operculum, but no peristome. 3. Andrsese, split-mosses ; 

 csespitose mosses, sporangia bursting vertically into 4 valves, central 

 columella, spores without elaters. Genera, 130; species, 2500. British 

 genera, 110; species about 570. Examples — Phascum, G-ymnos- 

 tomum, Splachnum, Orthotrichum, Dicranum, Bryum, Funaria, 

 Polytrichum, Hypnum ; Sphagnum ; Andrsea. 



Order 220. — Hepatic.*;, the Liverwort Family. Plants having 

 an axis which either bears cellular leaves (fig. 889) or is leafless, and 

 is bordered by a membranous expansion or thallus. Stomata are found 

 in the epidermis of some. The reproductive organs are — 1. Antheridia 

 (fig. 490, p. 276), which are either embedded in the frond (fig. 489, 

 p. 275) or situated on rounded sessile and stalked receptacles (fig. 

 488, p. 275). 2. Archegonia (fig. 492, p. 276), either inclosed in 

 involucres and solitary (figs. 493, p. 277 ; 889 i i), or occurring at the 

 edge of the frond, or on the lower side of stalked peltate expansions 

 (figs. 448, p. 251 ; 491, p. 276). Thecse or sporangia, having no 

 operculum, opening irregularly, or by four valves (fig. 889). Spores 

 (fig. 594, p. 334) often mixed with spiral filaments called Elaters 

 (fig. 890). Heterorhizal in germination (fig. 629, p. 356). — Terrestrial 

 plants, found in damp places, or inhabiting water ; some having a 

 moss-like appearance. They are natives both of cold and warm 

 climates, and are generally distributed over the globe. 



The order has been divided into three sections : — 1. Marchantiese, 

 Liverworts : thecse collected in heads, bursting irregularly, no oper- 

 culum, spores with elaters. 2. Jungermannieee, Scale-mosses : thecae 



