232 ME. H. N. Dixox ON MOSSES [June 191 2, 



was collected. The foregoing Table gives, I think, some reply to 

 these problems. Leaving the Upper Bed out of the question for the 

 present, it will be seen that of the forty or so forms determined 

 from the remaining three beds, fourteen at least occurred in all 

 three. Of about 24 species determined from the Middle Bed, 16 at 

 least are also in the Lowest, and 15 at least in the General Collection. 

 Of about 32 determined from the General Collection, all but six 

 occurred either in the Middle or Lowest Bed : of these six, five 

 occurred very sparsely ; in every case, I think, a single fragment 

 only — the remaining plant, Hypnum sendtneri, being the only 

 species which occurred with some frequency in one of the Beds 

 without being found — or at any rate, without being frequent — 

 in the others. 



The conclusion I think is inevitable, that the floras from which 

 the plants of the General Collection, the Middle, and the Lowest Beds 

 were derived must have been practically identical. The General 

 Collection probably represents actually the same level and the same 

 deposit as the Lowest Bed, for out of its 32 determined species, 

 about 20 (and probably more) occurred in the Lowest also, rather 

 fewer being common to the General and the Middle. But I think 

 that in all probability the Middle Bed also represents the same flora, 

 either deposited at roughly the same time, or at a very slightly 

 later period, when not only were the conditions similar, but a 

 practically identical (not merely similar) flora existed in the neigh- 

 bourhood. Otherwise, it is scarcely conceivable that out of so 

 comparatively small a total of species noted so large a proportion 

 could be common to the Middle Bed and to the others : especially 

 when the fact is taken into consideration, referred to later, that in 

 both cases there are two distinct associations combined — one which 

 is probably more or less in situ, while the other must have been 

 brought from at least some distance. The comparatively small 

 amount of material obtained from the Middle Bed probably quite 

 accounts for the absence of some species found in the other two. 



The main characteristics of this flora represented in the General 

 Collection, the Middle and Lowest Beds, are that, in the first place, 

 it includes, as mentioned above, two distinct associations : (1) a 

 paludal or aquatic one with Harpidioid Hypna dominant, in 

 addition to other paludal species, Hypnum scorpioides, H.giganteum, 

 and H. cuspidatum ; (2) a terrestrial or more or less rupestral 

 association, of which several of the Brya^ Tortula aciphyllciy 

 Encalypta rliahdocarpa, Bistichium, etc., are characteristic. Some 

 of the last-named, especially, have no aquatic predilections, and in 

 no way depend on proximity to water ; while, on the other hand, 

 they are much too commonly represented here for their presence to 

 be merely fortuitous — the small fragments that from time to time 

 might be carried into a bog or marsh from a surrounding general 

 land flora by wind, or rain, or ice-action, could not account for the 

 large representation which some of these species have among the 

 paludal ones. 1 think that the explanation is certainly to be found 

 in a river, or tolerably large stream, flowing in some of its upper 



