63 



locations in the neighbouring strata. The period at which it 

 occurred was approximately given as between the deposit of 

 the Coal Measures and that of the succeeding New Eed 

 Sandstone and other rocks which show no signs of such dis- 

 turbance. The great diminution in thickness of the Secondary 

 Deposits to the north of the Mendip range, compared with 

 the same Deposits to the south, may be accounted for by the 

 Mendips having formed a Carboniferous Island in the midst 

 of the ancient seas, thus making a barrier to the irruption of 

 the secondary seas, so that the formation of a deep sea deposit 

 withm this barrier to the north was prevented. Various sec- 

 tions in ascending order from the Keuper to the Lias were 

 described, and the wonderful dykes -and fissures runnin<. 

 generally east and west in the Carboniferous Limestone in the 

 Hotwell and Vallis quarries were dwelt upon. The peculiar 

 features of these dykes having puzzled even the savans of the 

 British Association during their visit in 1864, allowance may 

 be justly made for the surprise with which the Members 

 present this evening heard that the painstaking researches of 

 the speaker had revealed to him at the bottom of one of these 

 Limestone fissures (270 feet below the surface) not only 

 a Liassic sea fauna of 95 species, but also three genera* of 

 terrestrial shells of the same age. The conclusion naturally 

 arrived at from this extraordinary discovery was that the 

 portion of the Mendips in which this fissure existed was a 

 land area during the Liassic period. In conclusion, Mr. 

 Moore paid a fitting compliment to the President of the Club 

 a feUow-labourer in the field of science, by asking permission 

 to name after him a new species of gasteropod (Fusus 

 Jenynsii) which he had found in the Southerndown and 

 Brocastle beds, a short description of which was given in the 

 course of the evening, and specimens in illustration of the 

 remarks were exhibited. 



'■e., '• Vertigo, Proserpina, and Helix.' 



