R. F. Tomes— Corals of Crickley mil. 297 



allowing it to adapt itself freely to its altered position on the 

 spheroid, partly by the viscosity of the liquid, and partly by 

 decrease in the moment of the forces shifting it ; then, the crust 

 having progressed as far as it was permitted to do, would stick 

 fast, and the whole would commence to rotate as a solid body, and 

 the principal axis, being that neither of the crust alone, nor of the 

 solid nucleus alone, but of the whole mass, would come to coincide 

 with the axis of rotation. 



Now when I look at the distribution of land on the globe, and 

 observe it chiefly confined to one hemisphere, and arranged in a 

 manner, not symmetrical, but with an approach to symmetry as 

 regards moment of inertia about the axis of rotation, I fancy I see 

 an indication of the truth of the supposition advanced. 



It is possible that a future generation of geologists may be able to 

 gather some information regarding the interior of the earth from the 

 mysterious phenomena of magnetic variation. But at present we 

 cannot hope for much help from this quarter. The temptation, 

 however, is too great to forbear quoting from Captain Evans's lecture 

 a very striking passage.' *' These are a few facts relating to secular 

 changes going on in two magnetic elements within our own time ; 

 and what are the inferences to be drawn therefrom ? They appear 

 to me to lead to the conclusion that movements, certainly beyond our 

 present conception, are going on in the interior of the earth ; and 

 that so far as the evidence presents itself, secular changes are due 

 to these movements, and not to external causes. We are thus led 

 back to Halley's conception of an internal nucleus or inner globe, 

 itself a magnet, rotating within the outer magnetised shell of the 

 earth." This is, to say the least, in very remarkable accordance with 

 the conclusion I have proposed to draw from geological and other 

 considerations. 



III. — A List of the M^drbporaria of Crickley Hill, Gloucester- 

 shire, WITH Descriptions of some New Species. 

 By Egbert F. Tomes, F.G.S., Corr. M.Z.S. 



A CONSIDERABLE part of the material forming the present 

 communication was collected as long ago as 1862, but the 

 specimens obtained at that time, with the notes thereon, remained in 

 abeyance until quite recently. On a renewed examination of them, 

 it appeared that much of what had been noted down had not been 

 superseded, and this induced me to go through the whole of it 

 again, and make such additions and modifications as seemed necessary 

 to bring it into its present form. And I have done this in the hope, 

 and indeed in the belief, that it will serve a twofold purpose. It 

 will make known some forms which are new, not only to the 

 particular locality, but also to the catalogue of English species ; 

 and it will furnish a more complete list than has yet appeared of the 

 species from one of the best-known Coral-reefs of the Inferior Oolite. 

 The Crickley Coral-reef, according to Dr. Wright, is the lowest of 



^ Lecture at the Royal Geographical Society, March 11, by Capt. F. J. Evans, 

 C.B., F.E.S., Hydrographer to the Admiralty, Nature, May 16, 1878. 



