FISSIDENS. 



[ 265 ] 



FLORIDE.E. 



arising vertically from the back of the nerve ; 

 3, the apical lamina, the preceding lamina 

 produced beyond the true horizontal blade 

 of the leaf in a two-edged form, on each side 

 of the nerve. Capsule equal, rarely annu- 

 late. British genus : 



FISSIDENS, Hedw. A genus of Fissi- 

 deiitese. Character that of the family. In- 

 florescence monoecious or dioecious, terminal 

 on the main stem or on short secondary 

 branches. Montague has separated the spe- 

 cies with an entire calyptra under the generic 

 name of Conomitrium. 



Fruit lateral. 



1. Fissidens taxifolium, Hedw. = Dicra- 

 num taxifolium, Sw. 



2. F. adiantoides, Hedw.=D. adiantoides, 

 Sw. 



Fruit terminal. 



3. F bryoides, Hedw. (fig. 245)=D.6ry- 

 oides, Sw. 



4. F. incurvus, Schwagr. = D. bryoides y, 

 Hook. Brit. VI. 



5. F.osmundioides,Hed\v.=D. bryoides ft, 

 Hook. Br. Fl. (Conomitrium, C. Mull.) 



6. F. Bloxami, Wilson, Lond. Jour. Bot. 

 iv. 195. 



FLANNEL, NATURAL. This term has 

 been applied to sheets or layers, of a harsh, 

 fibrous texture,sometimes found coveringmea- 

 dows, rocks, &c. after an inundation. It con- 

 sists of the interwoven filaments of Confervas, 

 with adherent or entangled Diatomaceae, In- 

 fusoria, crystals of carbonate of lime, &c. To 

 the naked eye it closely resembles a piece of 

 coarse or loosely woven cloth. Similar layers 

 are frequently found upon the margins of 

 pools during the summer. As the water 

 evaporates, the Confervae and other organisms 

 remain supported upon the stems of rushes, 

 or blades of grass, and when dry, form the 

 yellowish, greenish, or greyish layers of the 

 so-called natural flannel. 

 See PAPER, METEORIC. 

 FLAX. The liber-fibres from the stems 

 of the Flax-plant, Linum usitatissimum (nat. 

 ord. Linaceae, Dicotyledons). Under the 

 microscope, the fibres (PL 21 . fig. 2) are 

 readily distinguished from Cotton by the 

 form and consistence, being round and at- 

 tenuated to a point at each end, and of a 

 firm woody consistence which prevents them 

 from collapsing, and having pits in the wall. 

 New Zealand Flax is a totally different sub- 

 stance. (See PHORMIUM.) See FIBROUS 

 STRUCTURES, of Plants, and LIBER. 

 FLEA. See PULEX. 



FLINT. The organisms contained in 

 flint are the same as those met with in agate 

 and chalk ; and the remarks made upon their 

 relation to the formation of agate apply 

 equally to the case of flint. They consist 

 principally of the fibres, spicula, and gem- 

 mules of sponges ; the valves of the Diato- 

 maceae ; fragments of the shells of Mollusca 

 and Echinodermata ; the scales of fishes ; 

 and the sporangia of the Desmidiaceae, which 

 were formerly regarded as distinct organisms 

 (XANTHIDIA). 



In the examination of flint, thin sections 

 should be made by grinding and polishing ; 

 some kinds exhibit the organisms containedin 

 them best by reflected, others by transmitted 

 light. Some specimens, in which they are 

 abundant, will exhibit them well in chips 

 removed by a hammer. 

 See AGATE and CHALK. 

 BIBL. That of AGATE and CHALK; 

 Ehrenb. Ann. Nat. Hist. 1838. ii. 162; An- 

 sted, ibid. 1844. xiii. 248 ; Bowerbank, ibid. 

 1847. xix. 240. 



FLORIDE^orRHODOSPORE^. An 

 order of Algae. Red sea-weeds, some of the 

 common species of which must be familiar 

 to every one, as the delicate, feathery or leaf- 

 like plants brought away by most visitors to 

 the sea-coast; and the red colour, more or 

 less permanent or fleeting, is a pretty general 

 characteristic of this order, varying however 

 to purple, brown, and mixed tints of red, 

 green, and yellow, into dirty white. They 

 chiefly grow in deeper water than the other 

 sea-weeds, and are met with in finest and 

 darkest colour in deep tide-pools of sea- 

 water, especially on the side facing the north, 

 where they are overhung by the larger dark- 

 coloured Algae, and thus shaded from the 

 sun's rays. The greater number do not grow 

 more than six inches high, few more than 

 two feet. The simplest forms are filaments 

 composed of cylindrical cells attached end to 

 end ; they next rise to a gelatinous or car- 

 tilaginous expansion, composed of such fila- 

 mentous structures adherent in layers, and 

 forming a compact frond of definite shape. 

 These are said to be of filamentous structure. 

 Others have the frond composed of a num- 

 ber of polygonal cells, evenly arranged, and 

 with thick walls, or, as some state, an inter- 

 cellular substance binding them altogether 

 into a mass ; these are technically said to be 

 of cellular structure. Sometimes all the 

 cells of the frond contain colouring matter, 

 sometimes only those of the surface, or of a 

 shallow superficial stratum. 



