HANDBOOK OF BRITISH HEPATIC/E. 235 



Genus 32. GYMNOMITRIUM, Corda. 



Involucre many-leaved, leaves imbricate, 

 free, not adherent, involving the calyptra. 

 Perianth none. Capsule four-valved, cori- 

 aceous, naked. Elaters double, naked, 

 deciduous. — Acolea, Dumort. Syll. (1831). 



Diocious. Perianth wanting. Involucre double, 

 the inner shorter, composed of two or more involute, 

 deeply cleft, dentate leaves, which enclose the short 

 campanulate calyptra. Capsule globose, four-valved. 

 Elaters bispiral, falling away. Antheridia oval, 

 stipitate, in the axils of perigonial leaves. Stems 

 fasciculate, ascending, leaves in two rows, closely 

 imbricate, glaucous, creeping at the base, without 

 stipules. — Carr. Br. Hep. p. ./. 



Readily distinguished by the rigid julaceous, 

 thickly-matted shoots, resembling a plaited thong. 

 Colour also characteristic, silvery, creamy-white, 

 rarely darker grey or smoky. 



Gymnomitrium concinnatum, Corda. 



Barren shoots erect, simple or fasciculately 

 branched, slightly compressed, thicker and 

 obtuse at the apex ; leaves imbricated, ovate, 

 bidentate, sinus and lobes acute, border 

 narrow, membranous. Fertile shoots clavate; 

 involucral leaves larger, with reflexed margins, 

 upper connivent, irregularly dentate-lobate. 



Jungermaiuiia coiiciunata, Lightf, Scot. II., 



