PLAGIOCHILA. 451 
obtuse quadrangulum, solum apice compressum evenit ; plicis autem 
(nisi irregularibus in //. bursata et 2 vel 3 aliis) constanter 
orbatum. Foliolum florale posticum angustum interdum adest, vel 
tanquam ala interna intra perianthium adnata, vel utraque valvula 
margine connata, ita ut faciem perianthio tertiam suppetit, ad Lopho- 
colee instar. Calyptra a perianthio libera, duplo vel perpaulo 
brevior, globosa vel ovali-globosa, leptodermis preter ad basin ubi 
in collum breve carnosum, basi pistillidus sterilibus cireumdatum, 
perszepe constricta. Pedicellus validus, sub 10 cellulas diametro, 
ad maturitatem in omnibus fere brevis, perianthio subduplo longior; 
in Pl. aspleni‘oide et perpaucis aliis elongatus, subpollicaris. Capsula 
sat magna, globosa vel ovali-globosa, pachydermis, ad basin usque 
4-valvis, valvulis haud raro bilobis; paries e cellulis 3-8-stratis, 
quarum extimis duplo majoribus cubicis, columnis angularibus 
fulcitis ; interioribus tenuibus opacis fibra semiannulari (interdum 
ex p. obsoleta) farctis. Hlateres dispiri; inveniuntur etiam (in 
capsulz apice precipue) ex parte vel tota longitudine monospizi. 
Spore parve minutzve subleevissime. 
Hab. et Distr. Plantz pre aliis omnibus hepaticis sylvatice, inter 
tropicos et in zona temperata australi frequentes, in boreali rariores. 
In zonis temperatis rupicole et terricolz, in sylvis Amazonicis autem 
et Andinis semper fere arboricole, vel in truncis ramisque vivis, vel 
in prostratis putrescentibus vigentes ; dum paucee species ad rupes, 
vel in ipsa terra inveniuntur. De sua distributione speciali exposi- 
tionem pleniorem sub sectionibus proxime describendis inveneris. 
The species of this fine genus are notable for the presence of a stout 
creeping trunk, or caudex, densely radicellose on the underside, while the 
leafy stems that arise from it are, as a rule, quite rootless, except some- 
times at the very base. The caudex itself puts forth distant leaves, only 
one-third the size of the stem-leaves, attached by a broad base—decurrent 
on the upper side of the stem at an angle of 45°, on the underside shortly 
and narrowly arched—and sometimes reduced to a semilunate rim, but 
more commonly subquadrate, truncate or retuse, in some species rounded, 
and either toothed or entire. In age they usually decay long before the 
rest of the plant ; but sometimes a few such leaves extend also some way 
up the assurgent stems, giving the latter a tree-like aspect, and these 
are more permanent. The caudex is often subramose, in the same 
plane, some of the branches being occasionally rooting flagella. In the 
§ Heteromalle the erect stems put forth similar rooting stolons towards 
the base ; and sometimes leafless—or deciduously leafy—but rarely root- 
ing stolons up to the very top; but in all the other sections such stolons 
are very rarely present. 
The absence of rootlets from the stems and branches, although at first 
sight a constant character, is yet not without exceptions. Pl. tenuis 
Lindenb., in fertile specimens from Guadaloupe which I owe to the 
