Vol. 62.] STRUCTURE OP THE SGURE OP EIGG. 63 



to group the two together as probably having the same origin and 

 age. 



The fragments of brown wood mingled with sandstone-debris in 

 the breccia lie, as a rule, quite detached in the general matrix ; but 

 in one or two cases I thought, without being certain, that they were 

 partly embedded in the crumbling sandstone-fragments. Moreover, 

 one piece of wood, selected for slicing, shows the unmistakable 

 white sandstone actually embedded in the substance of the wood, 

 as if filling a hollow made by decay. This conclusion, in which 

 Mr. Seward concurs, would imply that the fragments of wood have 

 been derived, together with the sandstone, from Oolitic strata in 

 place, and are of that age. 



Mr. A. C. Seward, F.R.S., has had the kindness to examine thin 

 slices of this fossil wood, and I am permitted to quote here the 

 notes which he has drawn up. 



Brown wood from the Great Estuarine Sandstone of 

 Camas Sgiotaig, Eigg. 



' Imperfectly preserved coniferous wood. The material is not sufficiently 

 good to enable one to determiue the nature of the plant with any certainty ; 

 it is indubitably a Conifer, and from its arrangement of pits on the radial walls 

 of the tracheids I think that it is probably referable to the genus Araucaroxylon. 

 This generic type includes Araucaria and Agathis, the two surviving repre- 

 sentatives of the Araucariere, and numerous fossil species. I think it most 

 probable that the wood is of Jurassic age.' r 



Brown wood from breccia below the pitchstone of 

 the Sgurr of Eigg (Z in fig. 5, p. 57). 



' In one specimen the wood contains an included patch of rock which was 

 I believe, introduced during the decay of the tissue. The rock and wood are, I 

 believe, contemporaneous. The generic ideutitication is very difficult, not to 

 say impossible, owing to the lack of well-preserved material. The characters 

 do not agree with those of Pinites eiggensis, as represented by the well-preserved 

 specimens in the British Museum (Natural History). Similar characters are 

 shown in two other sections.' 



[Another specimen.] 

 ' Preservation very poor ; but, from the occurrence of multiseriate and 

 contiguous bordered pits on some of the tracheal walls, the wood appears to be 

 Araucaroxylon. This type exists in Palasozoic rocks, it occurs in the Mesozoic 

 and Tertiary formations, and is characteristic of the recent Araucarieas.' 



Conclusion. 



' The wood from Camas Sgiotaig may be generically identical with some of 

 the material from the Sgurr of Eigg : both show Araucarian characters. As 

 regards age, my impression is that the evidence favours a Jurassic rather than 

 a Tertiary horizon. The reasons in favour of this view are (i) the fact that 

 Araucarian wood is very abundant in Jurassic rocks (for example, the Liassic 

 rocks of Whitby, where this type of wood appears to have been mainly 

 responsible for the production of jet ; Araucarian plants also occur in some 

 abundance in Inferior Oolite rocks) ; (ii) the nature of the material, which is 

 more like that known to occur in Jurassic than in Tertiary strata^.' 



1 [Mr. Seward was apparently not aware that these specimens had been 

 collected (by Mr. Tait) from Jurassic strata in situ, a circumstance which adds 

 weight to his following conclusions. — A. H.~] 



