NATURAL HISTORY SOCIETY OF GLASGOW. 161 



epidermis proving that it had lain with the unibone lowermost, as 

 we find them to-day. 



The remaining strata of sand, mud, and gravel, nine to ten feet 

 in depth, are most interesting, alternating, as they do, with layers 

 of vegetable debris of thicknesses varying from a quarter of an inch 

 to twelve inches. The most prominent vegetable remains found 

 in these strata were great trunks of trees, which occurred at 

 different depths, and all bearing evidence of having been long 

 knocked about in the water before finally sinking. In every 

 specimen I examined the wood was of oak, and always denuded 

 of the bark; but I am informed that willow and Scotch fir have 

 also been exhumed. The inner wood of these old trees was invari- 

 ably sound — only an inch or two on the outside being decayed. 



The lower bed of vegetable drift contained very few leaves, 

 being mostly composed of worn twigs, hazel nuts, and acorns. 

 The larger twigs were rounded and worn to a greater extent than 

 would seem possible from mere floating about as drift wrack; and 

 I believe their present pebble-like form was attained only after 

 much rolling about at the bottom ©f the river, subsequent on their 

 sinkino- from over-saturation. The hazel nuts, which were found 

 in great plenty, had sometimes distinct marks of the incisor teeth 

 of some rodent, probably the squirrel. I found one worn fruit in 

 this bed that seemed to be the seed of the alder — Alnus glutinosa. 

 In a similar deposit at Hutchesontown Mr Bennie found a cone 

 of the Pinus sijlvestris. 



A noteworthy chemical action was observed in connection with 

 these plant remains. "When they lay in little pools, the iron with 

 which the water was impregnated had combined with the tannic 

 acid of the vegetable tissues, and formed tannate of iron, or ink, 

 which not only dyed the nuts and twigs of a deep black colour, 

 but also blackened the water in which they lay. Where this 

 phenomenon was observed, the drift generally lay in a " nest," or 

 shallow basin, formed seemingly by an eddy in the swollen river. 



It was in the largest of the leaf beds that, resting on a bed of 

 sand and gravel, the mosses were found in greatest abundance, 

 and in best preservation. On separating the layers, the mass was 

 seen to be composed in great measure of decayed leaves, with a 

 notable proportion of sand intermixed, and generally a sprig of 

 moss would show itself, fresh and green, between the laminae. 

 After exposure to the air and drying, the mosses lost this verdure, 



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