POLYTRICHUM. 27 



at first to consider it only a variety of P. attenuaium, and 

 we must confess that we can ourselves see no difference 

 whatever. Of this latter, which Mohr takes up from Hed- 

 wig under the name of formo-sum, he says in his German 

 Cryptogamic Flora, " obsoleta et adnata nee distante apo- 

 physi a praecedente (P. communi) statim dignoscenda et 

 bona omniuo species," although his only character by which 

 it may be distinguished from the formosum is, that the cap- 

 sule is obsoletely sexangular, a peculiarity which we cannot 

 find to exist in any of our specimens. Wahlenberg on the 

 other hand seems to be of opinion that it is only a slender 

 variety of P. attenuatum; and he founds the chief distinction 

 of the latter from P. commune in the diaphanous margin to 

 the leaves. 



P. alpinum; stems elongated, branched; leaves patent, su- 

 bulato-lanceolate, the margins plane, serrated as well as the 

 points of the keels ; capsule sub-ovate, with an indistinct 

 apophysis. (TAB. XI.) 



P. alpinum. Linn.Sp. Pip. 1593. Menziesin Linn. Trans. Hedio. 

 Sp. Muse. t. 19. Turn. Muse. Hib. p. 85. Engl Bot. t. 1905. Moug. 

 et Nestl n. 209. P. sylvaticum. Menz. in Linn. Trans, v. 4. t. J.f. 6. 

 P. arcticum. Swartz Muse. Suec. t.Q.f. 17. Mohr. 



HAB. In sub-alpine regions in England, Scotland, and 

 Ireland. 



The narrow leaves will distinguish this species from P. 

 urnigerum, as the branched and somewhat fastigiate stems 

 will from P. commune and its varieties. The stems are from 

 three to four inches in height, the capsule is exceedingly 

 variable in form. In English Botany it is represented as 

 quadrangular, but far more decidedly so than ever we have 

 seen it; not unfrequently it is ovate without any angles: 

 we have some specimens gathered on the highest summit of 

 Ben Nevis, in which it is almost exactly spherical; and Wah- 

 lenberg has met with specimens having capsules so cylindrical 

 that he mistook them for plants of P. urnigerum. The apo- 

 physis is very indistinct, sometimes obsolete. 



8. P. urnigerum} stems elongated, branched; leaves erecto- 

 patent, lanceolate, acute, their margins plane, serrated; cap- 

 sule erect, cylindrical, destitute of an apophysis. (TAB. XI.) 

 P. urnigerum, Menzies in L nn. Trans. Turn. Muse. Hlb. p. 86. 

 Engl Bot. t. 1218. Moug. et Nestl n. 28. Dill Muse. t. 55. f. 5. 



HAB. On banks and sides of streams, principally in moun- 

 tainous countries. Mr. Turner has found it on banks at 

 Gillingham, Norfolk. 



