AND ©ravels op akdtux, etc., in mull. 



291 



A new and very rare leaf at Mull is perhaps identical with the 

 Quercus grcenlandica, Heer, from Atanekerdluk, some of the speci- 

 mens of which seem, however, to have been placed in Castanta 

 Vngeri by that author, though they do not resemble the Miocene 

 Chestnuts of either Europe or America. The specimen is illustrated, 

 PI. XI Y. fig. 2, and the species I would suggest should for the present 

 bear the name of Quercites groenlandicus. There is another very fine 

 Castanea-like leaf in the limestone, which is too large to illustrate. 

 "We also appear to have forms identical with those erroneously 

 described as Alnus nostratus, Viburnum Tl hymperi, and Carpinus 

 grandis, together with the forms figured, PI. XIY. fig. 3, PI. XY. 

 fig. 2, and PI. XYI. fig. 1, which as yet seem peculiar. 



Among the leaves with highly characteristic venation are the 

 Zizyphus hyperboreus or Pcdiurus horealis of Heer, both of which 

 belong probably to the same species, Populus Richardsoni and P. 

 arctica, which also seem to be undistinguishable, and Cornus hyper- 

 borea. Perhaps the most beautiful and distinctive leaf-form, how- 

 ever, in the whole flora is the exquisitely marked leaf with triple 

 midrib and crenated margin shown on PI. XY. fig. 1. The colour on 

 the face is pure white, with veins black, but on the back the whole 

 leaf is plum-colour. These strongly marked characters seem to 

 justify us in regarding it as a species of Bcehmeria^ of the Erticese, 

 and may even serve to identify it with an existing species of 

 Japan. I propose for this species the name of Boehmeria antiqua. 



There are, in addition to these, a number of simple ovate leaves 

 resembling those of the Bay and Laurel, &c, PI. XYI. figs. 2, 3, 5, as 

 well as the Rhamnites of Forbes ; but it seems scarcely probable that 

 any of these are capable of generic identification from the leaves alone. 



The flora is distinguished, like all those of early Eocene and 

 Cretaceous age, by the absence of the so-called Cinnamon-leaves 

 and the Smilacece, which always enter into the composition of 

 Middle Eocene and Oligocene floras rather largely. There is, in 

 fact, not one type characteristic of the Middle Eocene, Oligocene, or 

 Miocene in England or Central Europe to be found in it, and it 

 shares with all floras of similar or earlier age the peculiar facies 

 given by the complete absence of leguminous pods*. 



The Ardtun deposit is known to be of newer age than the Chalk 

 of the same area, because it includes material derived from it : and 

 in the absence of evidence linking it with any later stage of the 

 Cretaceous, it must be regarded as Tertiary f. The particular stage 

 to which it must be assigned has to be determined chiefly on the 

 evidence of the fossil plants contained in it. It will be seen that 

 though we cannot exactly parallel the Ardtun flora with anything 

 else, its general facies is more that of a Cretaceous flora than of a 

 Tertiary one, and that its most characteristic types ceased to exist 



* The only figure throughout the ' Flora Arctica ' purporting to be part of a 

 fruit, " Leguminosites,s]).," is a torn fragment, which might equally be part of 

 i a leaf. 



t In the Trans. Edinb. Geol. Soc. vol. i. April 1867, Mr. T. Smyth maintains 

 that the Lower Basalts of Ardtun and of the sides of Fingal's cave in Staffa are 

 Upper Cretaceous, and the leaf -bed of Ardtun, Miocene. 



