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My attention was first directed to this moss by Mr. Wilson 

 of Warrington, who clearly distinguished it from the species 

 of Gymnostomum., to which it is, in natural affinity, most nearly 

 allied, and with which it has probably not unfrequently been 

 confounded by muscologists, namely G. truncatulum /3. It 

 requires, indeed, a minute examination to distinguish the 

 differences; but they exist so assuredly, that no one who has 

 seen the two together on the same field of the microscope, 

 would ever think of uniting them. To say nothing of the 

 more extended tufts of the present plant, and of its more 

 glaucous hue, the leaves are blunter at the extremity than in 

 G. truncatulum /3., they have a longer apiculus, a more 

 evident, though a very slender recurved margin, and a 

 structure of cellules so different, that a moderate power of 

 the microscope, which will render those of G. truncatulum /3. 

 (see the figure in the accompanying plate,) very distinctly 

 visible, is not sufficient to bring them at all into view in our 

 present plant, {Jigs. 3, 4.) Again, in G. Wilsoni the capsule 

 is more contracted at the mouth, the beak of the lid is longer, 

 and the calyptra is curiously papilloso-scabrous above. 



Mr. Wilson had named this new species of Gymnostomum 

 G. affine in his MSS., without being aware that Nees von 

 Esenbeck and Hornschuch had so named a moss allied to, 

 or a variety of, G. Heimii. Thus I am at liberty to dedicate 

 it to the very acute botanist who first detected and distin- 

 guished it, and to whom I am indebted for many valuable 

 specimens of British plants, and numerous and important 

 observations upon them. 



Fig. 1, G. Wilsoni : — natural size. Fig. 2, Single plant : — 

 magnified. Figs. 3, 4, Leaves. Fig. 5, Apex of a leaf. 

 Fig. 6, Capsule. Fig. 7, Operculum. Fig. 8, Calyptra. 

 Fig. 9, Leaf of Gymn. truncatulum (i. to show the differ- 

 ence in form and reticulations : — magnified. 



