128 Proceedings of the Royal PJiysical Society, 



tlie site of the old Borough Loch — were laid open by a series 

 of deep drains, the sections of which exhibited in the " lower 

 and earlier deposits a fine silt separated into laminae as thin 

 as pasteboard," crowded with impressions of the common 

 water flag and reed, then above the silt " a bed of grey marl 

 composed mainly of lacustrine shells with an occasional 

 land shell." Over this marl occurred in some parts three feet 

 of peat-moss, having still preserved in it the '•' glossy elytra of 

 beetles in their prismatic tints of azure and green." The silt 

 is considered to be a rain wash of clay and soil from the 

 crround surrounding;' the old lake. The marl is referred to as 

 the "dead exuvia3 of generation after generation of fresh- 

 water Mollusca for many ages, which at length filled up the 

 depths of the lakes till there was no place for the living ; then 

 water mosses sprang up in the marly shallows, and gradually 

 contracted its area, until what had been open water became 

 unsightly morass, and the old Borough Loch was transformed 

 into the Meadows." Mr Miller records two species of Cyclas, 

 three species of Limnea, but makes no mention of Ostracoda, 

 probably because in 1842 their significance as indicative of 

 lacustrine conditions was not recognised. 



The lake maxls we have examined are ten in number, and 

 were gathered within the last twenty years from the various 

 exposures which occurred during that time; not, it should be 

 mentioned, with the view of being described and their 

 organisms enumerated as in this paper, but partly as employ- 

 ment for leisure hours, and partly at the instance of Mr 

 David Kobertson, who was engaged in the study of the 

 recent freshwater Ostracoda, and who made some use of the 

 material collected. It was only within the last few months 

 that the idea of making this use of the surplus material 

 occurred to us as preliminary to a more exhaustive study of 

 the freshwater Crustacea of the Edinburgh district which 

 one of us (T. Scott) intends to make. Six of the marls or 

 silts were obtained from within or immediately around 

 Edinburgh; three — those of Corstorphine, Hailes, and Eedhall 

 — about four miles west of it; and one — that of Kethymyre — 

 about six miles to the north across the Forth, and is included 

 because it conforms, in the conditions and circumstances of 



