Edinburgh Geological Society/. 139 



In December, 1859, on the removal of Sir David Brewster to 

 Edinburgh, Professor Forbes was chosen Principal of the United 

 College of St. Salvador and St. Leonard, in the University of St. 

 Andrews. This office he held until his death, which took place on 

 the 31st of December last. He slowly declined from an irremedi- 

 able disease of the right lung. 



The society then proceeded to the consideration of ordinary business. 



The following communications were read : — • 



1. " On the Depth of the Seas in which the Carboniferous Lime- 

 stone was formed." By Alexander Somervail. 



Mr. Somervail said that by a careful study of the extent and thick- 

 ness of the Carboniferous Limestone, the organic remains with which 

 it is replete, and with what we already know regarding the bathy- 

 metrical distribution of life in our present ocean, and the deposits 

 taking place over its bed, we might form something like a correct 

 estimate of the comparative depth of those primeval seas. He men- 

 tioned that the late Professor E. Forbes held the opinion that the 

 Carboniferous Limestone had been formed in shallow seas not ex- 

 ceeding fifty fathoms in depth, being led to the conclusion by certain 

 mollusca of that period still retaining their colour markings, and by 

 observing that the testacea of our present seas, which have colours 

 and well-defined patterns, seldom inhabit greater depths than fifty 

 fathoms. He differed from this conclusion of Professor Forbes, 

 stating that the shells from the Carboniferous Limestone exhibiting 

 patterns of their colours belonged to feio individuals, and were 

 confined to a few genera, such as Terebratula, Aviculopecten, 

 Natica, etc. ; moreover, they could not be proved to have remained 

 in the original habitat in which they lived when imbedded in 

 the calcareous mud, but may have been drift shells carried far 

 from their own zones of depth. He remarked that the inference 

 of Professor Forbes was still further invalidated by the fact that 

 shells shewing distinct colours have been obtained from our pre- 

 sent seas at depths of one hundred fathoms and upwards. He 

 then proceeded to show that from the great extent and thickness 

 of the Carboniferous Limestone, the thorough marine character of its 

 fauna, and the total absence of land animals, and plants, that it must 

 have been formed under deep water, far from the shore, and little 

 influenced by rivers carrying sand and gravel, or the remains of 

 plants or other land organisms, which characterise the deposits of 

 shallow seas. He next alluded to the bathymetrical distribution of 

 life in our present ocean — the great depths from which living animals 

 have been obtained — and argued that the fauna of the Carboniferous 

 Limestone seas had as great a range in depth, and that the limestone 

 which is made up of their bodies or skeletons had been formed at 

 depths as great. He concluded by observing that instead of fixing 

 fifty fathoms as the maximum depth of the Carboniferous Limestone 

 seas, he should be rather inclined to regard this as the minimum 

 depth, while the maximum might be one thousand fathoms or even 

 greater. This he considered no exaggeration, but to be borne out by 

 all the phenomena presented by the Carboniferous Limestone, and 

 by the deposits at present forming over the bed of the ocean. 



