Musci Exorfrrer. 
POLYTRICHUM ANGUSTATUM. 
Polytrichum caule brevi, foliis lineari-lanceolatis undu- 
latis, siccitate crispatis, versus apicem dorso margine- 
que denticulatis, nervo lato lamellato, capsula erecta 
curvula, operculo brevi-subulato, calyptra glabra. 
(Tas. L.) 
P. angustatum. Brid. Hist. Muse. Suppl. \. p. 78. 
Sitpors® Sp. Muse. v. ii. p. 331. 
Has. Prope Boston in America septentrionali. D. Boott. (In 
Caroline humosis C/. Bosc. In Pennsylvania Muhlenberg. In 
Neomarchia leetum Ji/, Schultz. dedere.) Schwaegr. loc. cit. 
Caulis semiuncialis, simplex. Folia lineari-lanceolata, obtusi- 
uscula, carnoso-membranacea, fusco-viridia, parum concava,, 
revi-subulatum, capsule vix dimidiam lon- 
gitudine. Peristomium e dentibus 32 apice membrana hori- 
zontali connexum, 
The specimens here figured were communicated to my friend 
Mr. Lyell, by Francis Boott, Esq. of Boston, New England, a 
gentleman whose ardent thirst after botanical knowledge has in- 
duced him to visit this country; and who, in conjunction with. 
Professor Bigelaw*, of Harvard University, is now preparing for 
publication a Flora of the New England States. 
Although bordering very closely upon Polytrichum undulatum, 
this plant may with certainty be distinguished from it by the 
great breadth of the nerve and its distinct lamelke, and by the 
shortness of the operculum. To these characters may be added 
the much narrower capsule, its léss inclined direction, the nar- 
rower and more carnose leaves, and the much smaller size of the 
whole plant. Schwaggrichen does not seem in his specific cha- 
racter to have chosen those marks which will distinguish it from 
P. undulatum ; and he has introduced into his synonyms plants 
of Michaux and Dillenius, which appear to me to be only varie- 
os of P. undulatum, which is also a common plant in North 
merica. 
Fig. 1, plants nat, size. Fig. 2, inner view of leaf. Fig. 3, 
outer ditto. Fig. 4, eapsule, Fig. 5, operculum. Fig. 6, ca- 
lyptra.— magn. 
* Already known as th ay . 
Medi as ¢ author of Florula Bostoniensis and American 
