132 Reports and Proceedings — 



exceed iu destructive power the influence of oceanic waves and currents. 

 It maybe fairly questioned, however, whether some observers have given 

 due credit to all denuding agencies, in their explanations of the origin 

 of scenery ; or whether they have adequately appreciated the effects of 

 forces apart from those of denudation. If we cannot follow the Duke 

 of Argyll in all his interpretations of geological phenomena, we can 

 yet be thankful for the words of caution he has given in his eloquent 

 writings. There is no doubt that ice, rain, rivers, and sea have 

 performed the denudation. The question is, how far have other agencies 

 directed their action ? 



In the work before us Mr. Kinahan has endeavoured to demonstrate 

 that, in general, valleys are connected with faults or breaks, and that a 

 valley or hollow could seldom have been carved out unless there were 

 cracks, minor joints, or other shrinkage fissures, in which one or other 

 of the different denudants could work. He very fairly acknowledges 

 that meteoric abrasion (or sub-aerial denudation) seems to be the most 

 universal performer in the great work of denudation, but that without 

 the aid of faults and joints, . few valleys could have acquired their 

 present form. The fact that internal forces of disturbance may have 

 ceased to act long before present surfaces were formed, does not affect 

 the question of their influence. The author points out the relations 

 existing between breaks, faults, and lake-basins, particularly in Ire- 

 land ; nevertheless, ice-action and meteoric abrasion have been the 

 denudants, while the situation and shape have been influenced by the 

 earlier forces. 



Although objections may be taken to some of Mr. Kinahan' s con- 

 clusions, yet on the whole his book is a valuable addition to the litera- 

 ture of Physical Geology. The majority of the facts stated are from 

 the observations of himself and his colleague the late Mr. "Warren 

 on the Geological Survey in Ireland, and it is such experience gained 

 by detailed investigations that must always form the basis of our 

 theories, especially when taken in conjunction with the facts observed 

 in different parts of the world. 



IRIEIFOIEiT'S J^JSTJD PEOGEEDIUO-S. 



Geological Society of London. — L — December 16, 1874. — John 

 Evans, Esq., F.E.S., President, in the Chair. — The following com- 

 munications were read : — 



1. " Descriptions of the Graptolites of the Arenig and Llandeilo 

 Eocks of St. David's." By John Hopkinson, Esq., F.G.S., and 

 Charles Lapworth, Esq., E.G.S. 



Commencing with a brief historical account of the discovery of 

 Graptolites in the neighbourhood of St. David's, from their first 

 discovery in the Llandeilo series in 1811 by Sir Henry de la Beche 

 and Professor Eamsay, the authors proceeded to explain their views 

 on the classification of the Graptolites (Graptolithina, Bronn), 

 which they place under the order Hydroida, dividing them into two 

 groups, Ehaboophora (Allman), comprising the true siculate or 

 virgulate Graptolites, which they consider to have been free or- 

 ganisms, and Cladophora (Hopkinson), comprising the dendroid 



