06 D1DYMODON. 



Grimm ice (the Weissice of Hedwig), or, as we judge, ta- 

 king the approximation of the teeth in pairs and the habit 

 of the plant into account, that it should he left where Swartz 

 and Mohr have placed it, under the genus Didymodon. Itj 

 is an exceedingly rare species with us, having, since the time 

 of its discovery by Mr. Dickson, heen only met with hy 

 Mr. Mackay on the mountains of Cunnamara in Ireland. 



* * Capsules erect. 



3. D. nervosurn ; leaves obovate, shortly apiculate, their nerve 



incrassated above ; capsule ovate, erect ; lid shortly rostrate. 

 (TAB. XX.) 



Grimmia atro-virens. EngL Bot. t. 2015. 



HAB. On dry banks, especially in maritime situations. 



This species may easily be mistaken for IVeissia lanceo- 

 lata, and especially for that variety which has been called 

 W. aciphylla by Mohr 5 but the breadth and stronger tex- 

 ture of the leaf, its remarkable nerve, which is thickened 

 above, and its peristome of 32 teeth approached in pairs, are 

 abundantly characteristic marks. This species has wider 

 leaves than any of its congeners. 



4. D.jlexifolium; stems more or less elongated; leaves ob- 



longo-ovate, flexuose, strongly serrated at the point ; cap- 

 sule erect, cylindraceous; (lid rostrate, Dicks.) (TAB. XX.) 



Trichostomum flexifolium. EngL Bot. t. 2490. Bryum flexifolium. 

 Dicks. Plant. Crypt, fasc. 3. t. 7. 



HAB. On sterile banks near Croydon. Mr. Dickson. 

 Roof of an old barn near Manchester. Mr. Hobson. 



Stems from half an inch long in fertile plants to two inches 

 in sterile ones; leaves rather succulent, singularly flexuose H 

 and crisped, especially at their margins ; patent or recurved. 

 Nerve disappearing below the point. The margin at the; 

 extremity remarkably serrated ; fruitstalks about three quar-i 

 ters of an inch long ; perichaetial leaves longer than the rest,: 

 and convolute. Capsule ovate, cylindraceous, brown, smooth i| 

 in our specimens, striated in Engl. Bot. ; lid, according to > 

 Dickson, subulate. 



It is from Mr. Dickson alone that we have received fruc-J 

 lined specimens of this curious moss; but these had no 

 operculum nor peristome, so that the genus remains un- i 

 known. The leaves are totally unlike those of any other 

 moss. Mr. Hobson has lately found this plant abundantly' 

 near Manchester, but always barren. It grows in thick 

 tufts. 



