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THE JOURNAL OF BOTANY 



in wet, rocky places, and known by the filiform apex of the longly 

 acuminate stem -leaves. T. recognition then formed the residuum, 

 was nearly always bipinnate only, had moderately long, often 

 recurved apices to the stem-leaves, which, while often finely 

 acuminate, did not end in the long filiform point of T. Philiberti ; 

 and was almost entirely confined to dry, calcareous habitats, fre- 

 quently among grass in open places, but also, rarely, in calcareous 

 woods. In the former station it was usually sterile, in the latter 

 it was more frequently fruiting. 



Several recent works published on the Continent, however, 

 show that Continental bryologists have a different conception of 

 T. recognitum and T. Philiberti from that prevailing with us. 



a, a, Thuidium recognitum ; b, b, T. Philiberti : c, c, T. delicatulum . 



T. recognitum is described in these works as having the stem- 

 leaves plane- margined and small, the nerve broad above and 

 filling the acumen. It is further described as usually fertile ; 

 while T. Philiberti is spoken of as a more frequent plant, usually 

 sterile, with larger stem-leaves, having recurved margins, and 

 long, tapering points, with a weaker nerve which reaches only 

 part of the way up the acumen. 



After considerable correspondence and exchange of specimens 

 with Continental authorities, I have at last been able satisfactorily, 

 I think, to correlate our British plants with the Continental ones. 

 The main result that emerges is that the plant which we have 

 here considered as the common form of T. recognitum, the small, 

 bipinnate, sterile plant of dry (calcareous) banks, quarries, chalk 

 downs, &c., is really T. Philiberti ; the plant of wet mountain 



