The Scottish Naturalist. 



255 



for a considerable time, the ingenuity of Mr. Wilson, Mr. M'Kinlay 

 and myself. I allude to the endeavours then made towards re- 

 conciling the curiously graduated forms or varieties (call them 

 what you will) of Dicranum circinatum (Wils.). 



I trust I may be pardoned if I reopen the whole question, and 

 state candidly the conclusions then arrived at, as well as en- 

 deavour to throw, what I consider, additional light on the subject. 



Mr. M'Kinlay and myself detected nearly simultaneously a series 

 of forms of what Mr. Wilson determined as his D. circinatum. 

 In order the better to understand what follows, it will be as well 

 to indicate the series of forms by numbers from 1 up to 9, No. 1 

 indicating the normal condition of D. circinatum. 



On Ben Voirlich by Loch Lomond, and on Ben Donagh near 

 the head of Lochgoil, this moss was discovered under nearly 

 similar conditions, and generally on the ground beneath shelving 

 rocks. The patches spread continuously inwards from a little 

 beyond the verge of these rocks, to which the sun's rays had 

 direct access, up to where each was in contact with the ground; in 

 other words, they spread as far in as possible. In several in- 

 stances this extension inwards amounted to two feet. So far as I 

 can recall, the shady parts of the ground on which the moss 

 grew were free from any other kinds of vegetation. 



In the normal form, No. 1, the leaves are strongly falcate or 

 circinate, and the characters, microscopic and otherwise, are such 

 as are described by Dr. Braithwaite in Parts 6 and 7 of his work, 

 with the addition, however, in this form, as well as throughout the 

 series, of a cluster of largish pellucid, generally hexagonal cells 

 with thin irregular walls, disposed between the nerve and the 

 marginal smaller cells, and below the large rectangular cells. This 

 cluster of cells is apt to be lacerated, or indeed, to remain on the 

 stem, unless care be taken to separate the leaf slowly and in a 

 direction gradually backwards. This may be the reason why Dr. 

 Braithwaite has omitted mention of this group of cells, a group, 

 however, of considerable importance in the question of affinities, 

 and one which I shall call the auricular group. In this moss the 

 group is not strictly auricular, but inasmuch as it is the analogue 

 of what is truly the auricular group in others, e.g., in D. longirostre, 

 &c, I shall retain the term ; and, besides, I shall designate it 

 central when situated close to the nerve, and lateral when mar- 

 ginal, or bulging beyond the general margin. I am strongly of 



