Leucodon.] BRYACEiE. 287 



2. M. nigrescens, Mitt. Branches creeping; branchlets 

 long, flexuous, pinnately branching: leaves oj^en-spreading, 

 undulate lengthwise, cordate at base, lanceolate, narrowly acu- 

 minate, costate to above the middle ; borders flat, more or less 

 undulate, minutely crenulate ; pcrichretial leaves similar, thin- 

 ner : calyptra split on one side, covered with a few hairs : cap- 

 sule short-pedicellate, broadly oval, exserted above tlie hairs of 

 the vaginule; oi)erculum subulate. — Journ. Linn. Soc. xii. 441. 

 Jli/pnum nigrescens, Swartz, Prodr. 141. NecJcera nigrescens, 

 Schwaegr. Suppl. iii., t. 244. Trachgpus, Mitt. 1. c. viii. 45. 



Hab. Floritla (Garher, J. Donnell Smith, Austin, liussell); Lake 

 Huron, in fruit {Todd); Canada West (Emery). The distribution of this 

 tropical species so far north as Canada is remarkable. 



Tribe XVIII. LEUCODONTEiE. 



Primary stems creeping, the secondary erect or pendent, 

 simjjle or branching, irregularly or subpinnately ramulose. 

 Leaves close, open or secund, ovate, obovate or oblong-lanceo- 

 late, subscarious, solid, generally plicate lengthwise, glossy ; 

 costa simple or double, rarely none ; upper areolation rhom- 

 boidal or linear, the lower in rows, vermicular-linear, puncti- 

 form at the basilar angles. Flowers dioecious; pericha^tium 

 long, sheathing. Calyptra large, dimidiate, cucullate, its base 

 sometimes confluent under the capsule. Capsule more or less 

 long-pedicellate, erect or oblique by the curve of the pedicel, 

 symmetrical. Peristome simple or double, more or less perfect. 



108. LEUCODON, Schwaegr. (PL 4.) 

 ■ Secondary stems erect or arcuate, simple, generally stolon- 

 iferous, densely foliate. Leaves decurrent, ecostate, sulcate 

 lengthwise ; cells of the areolation narrowly linear-vermicular, 

 the middle and basilar punctiform. Calyptra solid, cucullate, 

 often attached below the capsule by the connate base. Capsule 

 coriaceous, oval-oblong, microstome, exserted or emersed on a 

 short straight pedicel. Operculum conical or obliquely short- 

 rostrate. Peristome simple; teeth thin, distantly articulate, 

 2-3-cleft at the ajDex, papillose, whitish. 



