; ' NEOLITHIC " MOSS REMAINS FROM FORT WILLIAM 107 



must have had such an origin. Many of the others are the 

 ordinary plants of the drier boulders of mountainous or sub- 

 alpine country through which such a stream commonly makes 

 its way (e.g. Hylocomium squarrosum, Antitricliia, Andrecea, 

 Rhacomitrium heterostichum) ; Andrecea RotJiii is a very 

 typically rupestral moss, and Hyocomium and the Blindia 

 are distinctively and exclusively mosses of waterfalls and 

 swiftly running mountain becks. But in addition to this 

 we must picture the stream as flowing through woods. For 

 Plagiothecium undulatum^ Hylocomium brevirostre and H. 

 loreuin, Eurhynchium striatum, E. myosuroides and E. 

 myurum, Thuidium tamariscinum and T. delicatulum, in- 

 fallibly tell of woodland, and rocky, mountain woodland, 

 while Neckera complanata, and especially N. pumila, must 

 have been growing actually on the trees themselves. We 

 may perhaps safely go a little further than this. Thuidium 

 Philiberti is especially a plant of wet rock ledges or dripping 

 cliffs ; SpJiagnum Girgensohnii (if our species be that) affects 

 the same habitats ; Thuidium delicatulum prefers, at least, 

 the margins of fair-sized streams. Out of about eighteen 

 gatherings I have made of this species in Great Britain, 

 fifteen were from the borders of fair-sized mountain streams 

 and one from a lake shore. 1 believe we may therefore 

 confidently reconstruct the conditions under which these 

 mosses grew as indicating a stream of some magnitude 

 not a mere rivulet tumbling over boulders, and flowing, 

 at times at any rate, between wet rocky cliffs, down a 

 wooded mountain side or valley. We should not have to 

 go very far from the locality where they were deposited to 

 find, at the present time, just such conditions. I have 

 gathered in woods on the south shore of Loch Leven, 

 above Ballachulish, and within a confined area, nearly every 

 moss contained in this collection, except Tlmidium Philiberti. 

 There, by a similar stream to the one pictured, Dicranum 

 Scottianum was fruiting abundantly, Fissidens osmundoides 

 was loaded with capsules, and Tliuidium delicatulum showed 

 its delicate fern-like fronds, while the Hylocomia and many 

 of the other pleurocarpous mosses listed above formed the 

 bulk of the Bryophytic vegetation of the woods. 



While, however, so much is certain, I believe, as to the 



