RARE OR SCARCE MOSSES. [AugUSt, 



The discovery of this pretty species is Mr. Nowell's. Having 

 myself observed the male plants stuck down on the same sheet 

 ■with British specimens of M. serratum in the herbarium of Sir 

 W. Hooker^ but unfortunately without a locality, I had urged 

 Mr. Nowell to search for it, and in a very short time he was so 

 successful as to find it on shady limestone rocks, Arnclifie, Craven, 

 with perfect fruit. I suppose it to affect montane and subalpine 

 situations. 



M. orthorynchum is distinguished from M. serratum by its di- 

 oicous inflorescence and much firmer cell- structure ; it is there- 

 fore a more rigid Moss. 



The present is perfectly distinct from the M. orthorynchum of 

 Wilson, Bryol. Brit., excepting so far that the foreign fertile 

 plant therein delineated may belong to it, 



Mnium riparium, Mitten. — M. 07'thorynchum, Wilson, Bryol. 

 Brit., so far as concerns the British specimens, also formerly 

 distributed by me as M, heterophyllum, Hook. 



Besides the localities already indicated I have no others to 

 offer, excepting that some probably Irish specimens exist amongst 

 the residue of Drummond's Mosses, without locality. 



That this moss was distinct from M. orthorynchum I have al- 

 ways maintained ; for a comparison of the leaves shows the cells 

 to be about three times larger than in that species; in this par- 

 ticular it resembles M. serratum, but in that the inflorescence is 

 synoicous, whilst male plants only of M. riparium are known to 

 grow in Britain. The characters therefore to be ascribed to 

 M. riparium are, — habit and size that of M. serratum, inflores- 

 cence dioicous, cells thrice as large as those of M. orthorynchum. 



About two years ago I sent this Moss to M. Schimper, with 

 the present name, M. riparium, Mitten, MSS., and he stated in 

 reply, that he had received the same species, in fruit, from Mr. 

 Sullivant, United States, and proposed to name it M. Sullivantii. 

 Nothing however has since transpired respecting this ; it is not 

 noticed in the CoroUarium, ' Bryologia Europsea,^ nor is there 

 any notice of such a species in Sullivant's beautiful ' Musci and 

 Hepaticse of the United States,^ recently published. I have 

 however examined several specimens of M. serratum, sent by 

 Mr. Sullivant, which have a very great external resemblance to 

 M. riparium, which nevertheless disappears when the plants have 

 been carefully examined. This Moss is to be sought by the sides 



