Ortttotrichum.] DIPLOPERISTOMI. 1 29 



HAB. Trunks of trees. 



The stems vary considerably in length, from one to three 

 inches ; and are only exceeded by those of O. Lyellii. The inner 

 peristome is of a very peculiar structure, broad, pale-coloured, 

 and composed of moniliform joints, usually arranged in single 

 rows, but not unfrequently having other joints attached to 

 their sides. Moreover, the ciliae do not arise from the sides of 

 the exterior teeth, as in most other European species of Ortho- 

 trichum, but originate below their sinus, and from a different 

 and an interior membrane, as in Hypnum. 



9. O. Lyellii; stems erect (elongated,) leaves linear- lanceolate 

 subundulate carinated very acute crisped when dry, capsule 

 oblong furrowed, ciliae filiform, calyptra very hairy. (TAB. 



XXII.) 



Orthotrichum Lyellii. Hooker and Tayl. Muse, Brit. ed. 1. jp. 76. 



Moug. et Nestl n. 619. Hobson, Muse. Brit. r. 2. n. 47. Hook. Fl. 



Scot. P. II. p. 137. Arn. Disp. Muse. p. 18. Drummond, Muse. Scot. 



v. 2. n. 57. Hook, and Grev. in Edin. Journ. of Science, v. 1. p. 124. 

 HAB. On trees in the New Forest, Hants. Mr. Lyell. 

 About Oxford. Mr. Oglander. Common in similar 

 situations in Scotland. 



This fine species, to which we have given the name of its 

 estimable discoverer, has many points in common with O. 

 striatum ; and yet is, at first sight even, so easily distinguished 

 by its long, narrow, and crisped leaves, and sessile fruit, that 

 we think no one will hesitate in pronouncing it as decidedly 

 marked a species as any in the genus. It has been found in 

 North America by Mr. Menzies, and has been published in 

 Germany by Mougeot and Nestler. Mr. Arnott has gathered 

 it in the forest of Montmorency near Paris. 



The stems are from two to three and even four inches in 

 length, and are certainly among the largest of the genus, much 

 branched ; with the branches, when growing on the trunks of 

 trees, turned upwards in a dry state, as in Leucodon sciuroides. 

 Below they are destitute of foliage, in consequence of the plant 

 growing in a crowded manner; above densely clothed with 

 long, linear-lanceolate, recurvo-patent, undulate, and when dry, 

 crisped leaves, whose margins are not, (as in almost all the 

 other species,) recurved, but rather have a tendency to be in- 



