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ME. J. S. GAEDNEE ON" THE LEAE-BEDS 



low lands which the river must have sought would inevitably have 

 sunk under the enormous weight of Trap poured out upon them ; and 

 in this area at least it is highly probable that we have little more 

 accessible to us than the flows which cluug to the flanks of the 

 hills. 



The Flora of the Arcltun Leaf-beds. 



Considerable collections from these beds were made some 35 years 

 since and were deposited in the Museum at Jerinyn Street and at 

 Inverary. About five years ago Mr, Koch made a large collection, 

 which he presented to the University Museum at Glasgow. No 

 specimen was to be found in the British Museum or in the Edinburgh 

 Museum, and the flora was equally unrepresented in even the most 

 complete of our University and great provincial museums. The 

 collections that did exist were from the beds shown in figure 3, and 

 the bed marked d in figure 6, the matrix, in most cases, being a 

 crumbling black shale, in some a hard grey rock ; and the specimens 

 of leaves were, with few exceptions, of a fragmentary description. 

 I first endeavoured to supplement these in 1883 and 1884, but it 

 was not until 1885 that regular quarrying operations were under- 

 taken, with the result that large and perfect specimens of the chief 

 types have been procured in abundance, and are now in the British 

 Museum. One specimen in particular, nearly a yard in extent, 

 shows several forms of Platanites and fronds of Onoclea in perfect 

 preservation. Whilst collecting these, I excavated the beds marked 

 / to i in fig. 6, which, though apparently observed by the Duke of 

 Argyll, were at that time regarded as inaccessible. The layer g is 

 a limestone as finely grained as that at Solenhofen, and contains 

 impressions of leaves as beautiful as can be imagined, though it is 

 unfortunately refractory and breaks with a conchoidal fracture, 

 which baffles the search for fossils in it unless extreme care is used. 

 Even when found, the absence of cleavage-planes makes it difficult 

 and tedious to expose them. On the other hand, square yards at a 

 time may be exposed of the underlying pale grey clay, completely 

 covered with magnificent-looking leaves, preserving the colours 

 proper to them when they sank waterlogged in the stream ; but 

 here disappointment attends every attempt to remove them, for the 

 clay instantly breaks up into pieces a little bigger than dice, and 

 continues to crumble. The mere sight of such masses of leaves is 

 most instructive, and from notes taken on the spot I am able to 

 speak of the relative abundance of species, their variation, colour, 

 and the maximum sizes attained by them. I also ascertained by 

 this means that our knowledge of the flora is still relatively very 

 imperfect. We are, however, now in possession of a large number of 

 specimens, especially from the limestone, the nature of which I have 

 endeavoured to convey in the accompanying Plates (Pis. XIII.- 

 XYI.), in which only those of moderate size could be included. 



The beds share a peculiarity possessed by most of the Eocene 

 plant-beds in England, namely the absence of traces of aquatic life. 

 It is difficult to come to any conclusion regarding the cause of this ; 



