Musci Exorict.—Menzeesiani. 
POLYTRICHUM LAEVIGATUM. 
Polytrichum caule simplici, foliis arete imbricatis ovatis 
concavis integerrimis, nervo crasso lamellato, capsula 
late ovata cernua, calyptra levi. (Tas. LX XXI. 
P. levigatum. Wahl. Fl. Lapp. p. 349. 
P. glabratum. Wahl. MSS.—Mackenztes Iceland, 
p. 454. 
Catharinea glabrata. Hook. Tour in Iceland, vol. 1. 
p. 24, 
Has. In nuda arena riparia aprica fluminis Muconio, prope pa- 
gum Muconio superiorem et Ketkes-servando, Lapponie sylva- 
tice Tornensis, frequentissine. Wahl, 1, c.—Locis sterilibus 
Islandia, 
Radix densissime tomentosa. Caules cespitosi, bi-trilineares, 
simplices, curvuli, Folia arcte imbricata, erecta, appressa, 
pallide fusco-viridia, vy. lutescentia, ovata, concava, subcar- 
nosa, omnino integerrima, nervo lato intus insigniter lamellato, 
lamellis undulatis. Perichetialia reliquis minora, angustiora, 
fuscescentia. Seta crassiuscula, subtrilinearis, flexuosa, rufo- 
fusca. Capsula rufo-fusca, late ovata, horizontaliter inclinata. 
Calyptra omnino pilis destituta. 
ET 
P. levigatum affords an excellent specimen of the curiously 
lamellated nerve of the leaf, which in a greater or less degree is 
common to all the species of the genus which have come under 
my observation. Wahlenberg, its first and indeed only describer, 
mentions the back of the leaf as having this appearance, if I un- 
derstand his words rightly, ‘ foliorum dorsum undulatim dila~ 
tatur,” which is not the case with my specimens ; yet there can, 
I think, be no doubt as to the identity of the plant. Schwae- 
gtichen has quoted it, though doubtfully, under the P.levigatum 
of Bridel, which has leaves that are marginate and serrulate, and 
with which it can therefore have no affinity. 
_ Fig. 1, tuft of plants, nat. size. Fig. 2, the same, magn. 
Fig. 3, leaf. Fig. 4, section of a leaf to show the structure of 
the nerve, Fig, 5, periehatial leaf,—magn. 
