The Scottish Naturalist. 257 



to it; this holds true also in tufts of D. arisiaium in the usual low- 

 land habitats. 



Such is a brief outline of the characters observed in the various 

 parts of one of these tufts from without inwards. Besides the 

 gradations indicated, there are others intermediate between them 

 which the eye can appreciate, but which cannot be adequately 

 described ; in fact the transitions are too finely shaded off to 

 admit of a hiatus in almost any direction ; and the mind is 

 almost irresistibly drawn to the conclusion that the series repre- 

 sents states or conditions of one and the same plant. 



But the series is not yet completed. On rocks fully exposed to 

 the sunlight, and covered by a sprinkling of earth, there grows the 

 most robust form (or species) of all, in situations not far from the 

 other habitats already spoken of. 



In this, the robust stems which are often dichotomously 

 branched, are, in a dried state, of a tawny colour above, and of a 

 dark, dusky brown, or even black, below. The leaves are not 

 deciduous, but are firmly attached to the stem, are longer than 

 any of the others, slightly secund or even, slightly falcate, especially 

 at the apex of the stem, have no expanded bases, but are lanceo- 

 late throughout or lanceolate-acuminate. The bases are similar 

 microscopically to those of D. circinatum, although the rectangular 

 median cells are fewer and larger, while the marginal cells are 

 similar. The auricles are central, feebly developed, and colour- 

 less. The nerve is broad and flat, being one-third base of leaf, 

 predominant upwards; margin involute above; arista spinulose on 

 back and margin, especially in the younger leaves, and quite as 

 much so as in D. atistatum. In the older leaves these pellucid 

 unicellular spines or teeth are fewer, and at times disappear as in 

 D. longirostre. I distinguish this by the name D. capnodes. 



It is somewhat extraordinary that in the Lowlands, such as 

 Lennoxtown woods, there occurs a curious form of D. aristatum, 

 analogous to the species just described ; viz., where the leaves are 

 nearly lanceolate throughout, including the base. In this form the 

 irregular auricular spaces are sometimes well developed, although 

 they are much oftener absent, presumably because they remain on 

 the stem in the act of separation. Let this form be distinguished 

 by the name D. notabile. 



I possess another Dicranum whose characteristics cannot, in my 

 opinion, be reconciled to those of D. arctiami (Sch.), with which, 



R 



