﻿1851.] 



DUKE OF ARGYLL ON ARDTUN LEAF-BEDS. 



103 



covered by a bed of clay full of vegetable fibre, which forms the 

 surface of the ground. The leaves however, which when still wet 

 can be lifted from each other quite perfect, belong to a very different 

 age from those at Ardtun ; being apparently all of such plants as now 

 grow in marshy situations in the West Highlands, — bog myrtle, 

 willows, alders, &c. The Ardtun leaves belong to species and even 

 families which have long ceased to be indigenous in that country, and 

 indicate the occurrence of changes since the period of their growth, 

 not less great in climate than in the geographical forms of land and 

 sea. 



Note on the Fossil Leaves represented in Plates II. III. and 

 IV. By Prof. E. Forbes, F.R.S., V.P.G.S. &c. 



From among the numerous vegetable remains contained in the Ard- 

 tun beds, a few of the most perfect impressions of plants, mostly of 

 leaves only, have been selected for illustration. In accordance with 

 custom, specific names are assigned to these provisionally, for the 

 sake of distinguishing between the kinds found, and of comparing 

 them with fossils of a similar kind found elsewhere. Without much 

 more data than such impressions, however perfect, afford, anything 

 like a specific diagnosis, satisfactory to a botanist, could not be con- 

 structed. The general assemblage of leaves when judged by the 

 present state of our knowledge of the vegetation of ancient epochs is 

 decidedly tertiary, and most probably of that stage of tertiary termed 

 Miocene. Their climatal aspect is more mid- European than that of 

 our eocene flora. There is a striking resemblance between many of 

 them and fossils from Styria and Croatia ; but so far as I have had op- 

 portunities of comparing either with specimens or good figures, the 

 Mull fossils are in all probability distinct from any recorded species. 

 I cannot identify any of them with British eocene forms. 



Plate II. fig. la, lb. Taxitesl Campbellii. Fragments of a co- 

 niferous tree, possibly a Taxus ; allied to the Taxites Rostkorni of 

 linger, from the miocene lignite of Carinthia. 



Plate II. fig. 2 a, 2b. Part of a frond, probably that of a fern, 

 but presenting some anomalous features which future specimens will 

 probably explain. For the present it may be called Filicitesl hebri- 

 dicus. 



Plate III. fig. 1. An inequilateral leaf, the affinities of which 

 are doubtful. 



Fig. 2. Rkamnites 1 multinervatus. 



Fig. 3 . Rkamnites 1 major. 



Fig. 4. Rkamnites ? ? lanceolatus. 



Fig. 5. Platanites hebridicus, var.? 



Fig. 6a, 6b. Equisetum Campbellii. 

 Plate IV. fig. 1 . Platanites hebridicus. This leaf is one of the 

 most abundant and characteristic of all those found at Ardtun. It 

 has a close affinity with the Plat anus hercules (Unger, Chlor. protog. 

 p. 138. t. 46) from the marly slates (said to be eocene) of Croatia. 



Fig. 2. Affinities doubtful. 



Fig. 3. Alnites 1 MacQuarrii. 



