HANDBOOK OF BRITISH HEPATIC*!. 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, whk:h 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. 4.. 



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. 



Jungermannia concinnata, Lightf, Scot. II., 



