66 APLOPERISTOMI. [Grimmia. 



Schistidium nervosum. JBrid. Meth. p. 21. 



HAB. a. on trees and rocks in moist places, as well as in 

 alpine rivulets. )8. on rocky places in elevated moun- 

 tains. 



We heartily accord with Bridel when he says of this species 

 " adeo diversiformis et pro sedis conditione ita varians ut verus 

 Proteus sit." Upon trees and on humid rocks the stems vary 

 much in length, being from one to two or three inches long, 

 usually every where clothed with leaves ; these leaves, more- 

 over, are at their summits not unfrequently terminated by dia- 

 phanous points ; from these slight differences, added to the 

 more or less branched habit, have arisen the Grimmia alpicola, 

 and apocaula of authors. When growing on rocks, in moun- 

 tain streams, its length is still greater, the branches somewhat 

 more fastigiate, the leaves decayed at the base, every where 

 of a darker colour, and never furnished with diaphanous points ; 

 hence, the Gr. rivularis of authors : whilst on elevated moun- 

 tains a variety has been found (the Gr. stricta of Mr. Turner,) 

 whose slender, often straight and brittle branches, and red 

 brown colour, might at first lead to the suspicion of its being a 

 distinct species ; but its leaves differ in no essential particular, 

 and the capsule in all the varieties is liable to no small degree 

 of difference in form, being more or less ovate, but sometimes, 

 especially when the lid has fallen, turbinate. The Gr. gracilis 

 of Schwaegrichen we rather refer to our var. a. on account of 

 its colour. Wahlenberg has considered the Gr. stricta, and 

 Gr. rivularis as varieties of his Gr. alpicola, and has separated 

 them all from Gr. apocarpa on account of their want of the 

 diaphanous points to the leaves. 



2. Gr. maritima; stems short pulvinate, leaves lanceolate acu- 

 minate nearly erect crisped when dry, their margins recurved, 

 those of the perichsetium with the nerve running beyond 

 their summits, capsule ovate sessile, lid shortly rostrate. 

 (TAB. XIII.) 



Grimmia maritima. Turn. Muse. Hib. p. 23. t. 5. / 2. Smith, Fl 

 Brit. p. 1195. Engl. Bot. t. 164-5. Drummond, Muse. Scot. v. 1. p. 

 25. Hook. Fl. Scot. P. II. p. 129. Am. Disp. Muse. p. 20. 

 Schwaegr. Suppl v. 1. p. 95. t. 22. Brid. Meth. p. 32. 

 Gr. alpicola $. WaltL Fl. Lapp. 



