104 Transactions. 



sti-ata, either of shell limestone, of argillacious limestone, thought 

 from its fossils to be of fresh water or estuary origin. Unless in its 

 fine white sandstone got in the neighbourhood of Edinburgh, and 

 sent over the country for building purposes, in its fine grained 

 estuary and shell limestones (Burdiehouse and Burntisland), and 

 in the greater profusion of its shells and fishes, the lower 

 group, as developed in Scotland, diifers little in appearance from 

 the upper group. Hence the term lower coal measures generally 

 applied to it in this country. If we look at the lower coal measures 

 in the mass there cannot be a doubt that they were laid down 

 under very difi;erent conditions from the old red sandstone beneath 

 and the mountain limestone above. Both of these formations are 

 truly marine, the yellow sandstones being filled with true oceanic 

 fishes, and the mountain limestone crowded with marine shells 

 and corals. The lower coal measures, on the contrary, have more 

 of a fresh water than of a salt water aspect. Coralloid corals are 

 seldom obtained in their strata ; their shells are mostly esturine ; 

 their plants seem to have grown and flourished in marshes and 

 delta jungles, and many of their fishes are large and of a saurial 

 description. Under these circumstances, we may be quite 

 safe in regarding it as a separate group. As a whole, 

 the lower coal group in Scotland is eminently characterised 

 by fresh water or estuary remains, though in several 

 parts we may find seams of limestone and ironstone occur 

 frequently, containing encrinal joints, retijwra, palmchinas, 

 murchisonia, and others ; thus showing that during the laying 

 down of the strata there were various alternations of marine and 

 fresh water conditions. The plants of this group are much the 

 same as those already before described. Of the animal remains 

 the most characteristic are most minute crustaceous Cypris, Scoto- 

 burdigatensis, and Hibhertii, which abound in all the limestones and 

 shales. There are, however, frequent inter-stratifications of igneous 

 rock and precipitated showers of volcanic ash, as if the seas and 

 esturies of deposit had also been the seats of submarine volcanoes 

 and craters of eruption. The iron which impregnated the waters 

 of the old red period, and coloured with rusty red the whole of 

 that system, now appear in the segregated form of thin layers 

 and seams of ironstone. At this point I think we might say a 

 few words on some of the Dumfriesshire limestone quarries, which 

 I visited some time ago, then pos.sessed by the late Mr 



