Geological Society. 221 



thickness of 843 feet, which constitute the lower greensand in this 

 section, the results of a chemical examination of the several strata 

 were stated. The strata were grouped under three divisions, the 

 lowest consisting of fossilifcrous clays, the middle of Gryphsea sands, 

 and the upper of more or less fen-uginous sands, mostly free from 

 fossils. An inquiry was entered into respecting the conditions under 

 which these heds were deposited, and the state of animal life in the 

 cretaceous seas during their formation. The distribution of their 

 fossils was given in detail, and the results of the inquiry stated as 

 proving the unity of the lower greensand, considered as a member 

 of the cretaceous series. Capt. Ibbetson laid before the Society a 

 model of the section, on the scale of three feet to the mile, con- 

 structed by himself from trigonometrical survey, on which the several 

 strata described in the paper were laid down minutely. 



5. " Description of the mouth of a Hybodus, found by Capt. Ibbet- 

 son in the Isle of Wight." By Sir Philip Grey Egerton, Bart., M.P. 



This fish was found at the junction of the Wealden with the lower 

 greensand. The specimen sets at rest the question of the relative 

 characters of the upper and lower teeth, and the general contour of 

 the individuals composing the genus Hybodus, confirming the views 

 of Prof. Agassiz. The species is new, and Sir Philip Egerton pro- 

 poses to name it Hybodus Bassanus. 



6. The President read extracts from letters lately addressed by 

 M. Dubois de Montperreaux and by Prof. Agassiz to Capt. Ibbetson, 

 on the subject of the Neocomian. The former of these geologists 

 states that the Neuchatel beds cannot be regarded as complete, or as 

 the type of that formation, which he considers is best developed in 

 the Crimea and Caucasus. The latter considers the Neocomian as a 

 peculiar stage, and that the very lowest of the cretaceous system*. 



May 15. — The following papers were read : — 



1. A letter from Dr. Ick on some new fossil Crustacea, from the 

 South StaflPordshire coal-field. 



2. " On the Geology of Cape Breton." By Mr. R. Brown. 

 The newest stratified rocks in the island of Cape Breton belong to 



the coal formation. The coal-field of Sidney occupies an area of 250 

 square miles, and appears, from the dip of the beds, to be a portion 

 of a still more extensive field. The coal measures repose on mill- 

 stone grit of variable thickness and great extent. Beneath the 

 millstone grit lies carboniferous limestone, associated with extensive 

 beds of gypsum and marls. These gypsiferous beds lie upon con- 

 glomerates, which pass downwards into slates, corresponding to the 

 grauwacke formation in Europe. In places the eruption of red gra- 

 nite has converted the schists into white marble. Igneous rocks of 

 Tarious forms, granites, porphyries, greenstone and trap, occupy a 

 ■considerable portion of the islandf. 



3. " On the anthracite formation of Massachusetts." ByMr. Lyell. 

 The author states that the fossil plants associated with the anthra- 

 i[* On the subjects of these papers on the lower greensand and Neoco- 

 mian, see Phil. Mag. S. 3. vol. xxiv. p. 222, 224, 308.] 



[t See p. 214, supra; also vol. xxiv. p. 146, 149.] 



