160 ^ THE GEOLOGIST. 



I, the destroyer, do it — without measure. 



I fill creation's cup of joy,— man's lot, 



That vibrates restlessly 'twixt pain and pleasure, 



Determine ;— in my youth his years forgot. 



Worlds crumble ; — Virtue mounts to Heaven ; — no sleeping 



In dust for me ;— but, with bright angels keeping 



God's throne, with God I dwell and perish not." 



How imperfectly can human expressions shadow out the inex- 

 pressible age of the " Bottom-rocks ! " What, then, was that old land 

 like? 



If for all these ages this globe has been cooling down, how much 

 nearer to the surface then must have been the isothermal line of 

 boiling-water temperature ? Put it at fifty feet beneath the " rind of 

 Earth then every spring and water-flow ovei' the bare and barren 

 sea-washed crests and ridges would be reeking with clouds of rolling 

 steam. The sea would be ever giving off dense vapours, which the 

 sun in vain would strive to dispel, — a thick mist would envelope the 

 world ! Nothing — no not even the lichen, would vegetate iipon the 

 glassy solid rock, — and every spot would be silent, barren, damp, and 

 glistening grey. 



Was this the state of the first land ? 



GEMS FROM PRIVATE COLLECTIONS. 



III.-PHACOPS CAUDATUS; FROM THE DUDLEY LIMESTONE. 



In the Private Collection of Professor J. Tennant, F.G.S. 



The beautiful specimen of Phacops cattdatits, which we figure in Plate 

 v., has long been in the private collection of Professor Tennant. It is 

 from the Upper Silurian limestone of Dudley, and would be a perfect 

 example but for the exception only of its having the segments of the 

 body somewhat bent inwards, and slightly distorted from their natural 

 positions by pressure. The lateral edges and their segments are 

 unfortunately obscured by being embedded in the matrix, so that 

 they cannot be accurately delineated. 



This characteristic species of Trilobite was first noticed by Brun- 

 nich, in 1781, under the name of Trilobus caudatus. . It was subse- 

 quently termed Asapkus caudatus by Brongniart, Dalman, Dr. Buck- 

 land, and other writers. Burmeister, how^ever, in his valuable work 



