422 Proceedings of the Royal Irish Academy, 
Hab. Trunks of trees, walls, and rocks. Erequent in many parts of 
Ireland, and generally distributed. 
2. H. tricho)na}ioides (Bill.). Muse, tab. 34, f. 7. Bryol. Europ., 
vol. V. MonogT., p. 3, tab. 446. Eabenhor., Bryothec. Europ., 
JSTo. 71. Oinalia tricliomanoides, Bryol. Brit., p. 410, tab. 
24. Hypnuni tricliomanoides, Turner, Muse. Hib., p. 145. 
Hook, and Tayl, Muscol. Brit., p. 152. 
Hab. Trunks of trees, hedges, bushes, and rocks. Very common 
in every part of Ireland. 
Tribe 13. Stekeodonteji;. 
62. Plagiothecium. Bryol. Europ. 
Capsule leptodermous, oblong or roundish, generally cernuous or 
inclined to horizontal; lid large, conico-convex, with a long or 
short beak ; annulus composed of single, double, or treble series 
of cells. Peristome double ; outer of 1 6-teeth ; interior peristome 
of 16 carinate cilia ; entire or approaching in pairs between the 
spaces of the outer teeth ; rudimentary ciliolse at base sometimes 
present. Leaves five-ranked, complanately distichous, sometimes 
secund, nerveless, or shortly two-nerved at the base, soft and 
flaccid, or firm ; areolation rather large, composed of rhom- 
boidal hexagonal cellules, the basal cells longer, more trans- 
parent and flexuose. 
This group is intermediate between the J^Teckerese and Hypnese, 
agreeing with the former in habit of stems and leaves, with the 
latter in fruit. 
Diagnosis of Species. 
Inflorescence dioicous. 
Stem procumbent, with subfasciculate 
branches; leaves ovate, acute, trans- 
versely undulated, with two short 
nerves at base ; capsule cernuous, stri- 
ated when dry; lid rostellate, . . 1. P. undulatum. 
Stem decumbent, with elongated branches ; 
leaves ovate-oblong, acute, subcomplan- 
ate, large, entire, two -nerved at base, 
bright green ; capsule oblong- cylindrical ; 
lid with a short beak, . . . . 2. P. sylvaticum. 
