SEIROSPORA. 



[ 689 ] 



SEPEDONIEI. 



donous Angiosperms, as Schizopeta/mn, the 

 cotyledons appear to be four, six, or more 

 in uuniber ; but the observations of Du- 

 chartre show that there exist only- two — 

 bifid, trihd, or multitid cotyledons. In 

 other cases, as in Orchis, the embryo remains 

 imperfectly developed, and appears as a 

 mere cellular mass Lu the ripe seed before 

 germination ; this is destitute of albumen ; 

 but in Orohanchc an amorphous embryo is 

 found imbedded in the albumen. 



BiBL. General icorks on Botany. 



SEIROS'PORA, Harv.— A genus of Ce- 

 ramiacese (Florideous Algae), containing one 

 rare species, <S'. Griflifhsiana, a little crimson 

 feathery sea-weed, composed of single j ointed 

 tubes, the joints being traversed by articu- 

 lated filaments. The spores are unknown; 

 but the tctraspnres, which serve to distin- 

 guish this plant from the CaUithamnia, occur 

 in terminal beaded strings, being formed 

 out of the ramuli. 



BiBL. Harvey, Mar. Alg. 170. 



SE'JUS, lioc\i,= Gamams, pt. (Koch, 

 Uehers. 92 ; Murray, Ec. Ent. 164.) 



SELAGINEL'LA, De Beauv.— A genus 

 of Lycopodiacese, distinguished from Lyco- 

 jjodimn by the presence of two kinds of 

 spores and the dissimilar habit. 



This genns includes only one of our 

 native Club-mosses, *S'. sjnnosus {Lye. selayi- 

 noides) ; but most of the so-called Lycopodia, 

 now so extensively cultivated in Wavdian 

 cases, fern-houses, &c., belong to this divi- 

 sion (fig. 428, p. 481). The principal parti- 

 culars relating to these plants, especially 

 the remarkable history of the reproduction by 

 the spores, are given under Lycopodiace^. 



BiBL. See Lycopodiaceje. 



SELEiSITE.— This well-known mineral 

 substance consists of crystallized hydrated 

 sulphate of lime. Its crystals belong to the 

 oblique prismatic system ; and the colours 

 exhibited by thin laminse, into which they 

 may be easily split, are very beautiful under 

 polarized light. Polarizing crystals and 

 organic substances, in which the thickness 

 is not suited to the production of distinct 

 colours under the polariscope, may be made 

 to exhibit them by placing a plate of sele- 

 nite beneath the object. For this purpose, 

 the plate is usually kept mounted in Canada 

 balsam. See Polarization. 



SELIGE'RIA, Br. & Sch.— A genus of 

 Leptotrichaceous Mos-^es, including certain 

 Weissice of authors ; having the leaves seta- 

 ceous, and the capsules pvrifoi-m. 



SENBTNE'RA, Woods— A genus of 



Jungermannieifi (Henaticae), mostly tropical ; 

 one species of wliich, «S'. {Jung. ) Wooddi, 

 occurs rarely in tlie mountains "of the S.W. 

 of Ireland (devoiil of fruit). 



BiBL. Hook. Br. Fl. ii. pt. 1. 126; Br. 



or seed-like fruits of the common groundsel 

 (Senecio vuJyaris) is sparingly clothed with 

 Haibs of a peculiar character. These ap- 

 pear to consist of two semicylindrical cells 

 apphed together by their flat faces, so as to 

 form a kind of tube with a vertical septum. 

 When placed in water they expand some- 

 what, and the contents are expelled from the 

 ends, consisting of an indistinctly spiral- 

 fibrous structure, which untwists and ex- 

 pands by the absorption of water, to twice 

 or three times the length of the hairs, in a 

 manner comparable in some degree to the 

 behaviour of the contents of the hairs of 

 Acanthace^. (Leighton, Ann. N. H. vi. 

 259.) 



SEPEDONI'EL— A family of Hyphomy- 

 cetous Fungi, consisting of a heterogeneous 

 assemblage of imperfectly known genera-, 

 and difierently defined, by different authors. 

 Those genera we have included in our list 

 are enumerated in Liudley's ' Vegetable 

 Kingdom ; ' but Fries includes Oidinm and 

 others. The general character of the family 

 is, that the plants produce spores lying im- 

 mediately upon the decumbent filaments 

 of the mycelium, or upon short pedicels. 

 Genera : 



Artotrogus. Entophytic; filaments creep- 

 ing, persistent; spores springing from tlie 

 middle of the filaments, simple, at length free, 

 spinous. 



Sepedonium. Filaments woolly, septate, 

 evanescent; spores globose, connate, scabrous, 

 stalked, solitary, at length heaped together. 



Fusisporium. Spores fusiform or cylin- 

 drical, glued together in heaps resting on the 

 gelatinous matrix. 



Epochnium. Spores heaped, oblong, api- 

 culate, septate, adnate to the matrix, inter- 

 woven with the effused, entangled, slender 

 filaments of the mycelium. 



Fsilonia. Spores simple, pellucid, not 

 glued together, at fi^st covered by the con- 

 verging filaments of the mycelium. 



Monotospora. Epiphytic ; filaments creep- 

 ing, evanescent ; spores globose, solitary, 

 terminal, at length free. 



Asferophorn. I'ilament' creeping, ramuli 

 branched, the fertile termiualing in a spiral 



2y 



