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 thi'one, with God I dwell and perish not." 
How imperfectly can human expressions shadow out the inex- 
pressible age of the " Bottom-rocks !" Wliat, 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 1 Put it at fifty feet beneath the " rind of 
Earth then every spring and water-flow over the bare and barren 
sea-washed crests and ridges would be reeking with clouds of rolling 
Bteam. 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 upon the 
glassy solid rock, — and every spot would be silent, barren, damp, and 
glistening grey. 
Was this the state of tlie 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 caudatus, 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 Trilobns caudafus. It was subse- 
quently termed Asapkus mudaius by Brongniart, Dalman, Dr. Buck- 
land, and other writers. Burmeister, however, in his valuable work 
