PROCEEDINGS OF METROPOLITAN SOCIETIES. 291 



such as do honour even to the nation which produced their author. 

 A discussion followed, which had been postponed from the previous 

 meeting, relative to a remarkable disruption of the tails of the Ich- 

 thyosauri, always at a particular vertebra ; from which it had been 

 argued, by Professor Owen, that not improbably a fin, analogous to 

 that of many Cetacea, had existed in the recent animal ; for it was 

 remarked that no indication of such an appendage was visible in the 

 osteological structure of the Cetacea, whence, had we been acquainted 

 only with the skeletons of those animals, as in the instance of the 

 Ichthyosauri, the former presence of so highly important a locomo- 

 tive organ would certainly never have been suspected. He was led to 

 surmise, therefore, in order to account for this constant disrupture of 

 the caudal vertebrae of these animals always at one place, and from 

 the appearance which the discontinuation presented, that a weighty 

 appendage must have broken down the vertebral column, when, the 

 dead animal having floated on the surface until decomposition had 

 loosened the attachments of its bones, and its investments having 

 been sufficiently coherent to have confined the gases disengaged by 

 putrefaction for the required period, it at length sunk on the bursting 

 of the skin ; and an argument was accordingly deduced from this 

 presumed circumstance, for the tranquillity of the waters at the time 

 this gradual process was going on. Sir Philip Grey Egerton, Bart., 

 Dr. Buckland, the Rev. W. Conybeare, Professor Phillips, and Mr. 

 Darwin, argued the possibility of this explanation, and concurred, for 

 the most part, in the view entertained by Professor Owen. 



April 25th. — Three communications of a descriptive nature were 

 read : the first, from Mr. Bowman, on the geognosy of the neigh- 

 bourhood of Abergavenny ; the second, from Mr. Malcolmson, upon 

 the structure of part of the county of Elgin, announcing that the 

 Wealden rocks are considerably developed in the north of Scotland, 

 deviating, in some instances, mineralogically, but enclosing numerous 

 fossils, identical with those found at Swanwich ; the third, by Mr. 

 Austin, related to the limestones of Devonshire, for the manner of 

 formation of which a novel theory was proposed, suggesting that they 

 had been originally deposited in their present inclining order of stra- 

 tification, upon a conformably shelving surface. Mr. Murchison 

 then stepped forward, to comment on what he termed some valuable 

 practical details that had been laid before the meeting : details in 

 which he felt particular interest, as tending to elucidate the geological 

 history of this country, respecting which they contained important 

 information. It was with pleasure that he bore testimony to the 



