140 Astronomical Society. 



the incumbent mass of oolite is removed, the surface of the lime- 

 stone beneath is found to be smooth, or slightly waved like the 

 sands of the shore after the tide has retired ; and the rock is pierced 

 by tubular perforations evidently the work of marine animals ; a 

 proof that the surface must have been exposed to their activity for 

 some time before the oolite was deposited. The beds of mountain 

 limestone of the ordinary character, in some places alternate with 

 dolomite, precisely resembling that which is found in the same geo- 

 logical situation near Dublin. And the fossils of this formation in 

 the Boulonnois are the same with those of Derbyshire, Gloucester- 

 shire, and Dublin. 



On comparing in a general view the strata of the opposite 

 coasts, it will be seen that those of the Boulonnois do not occur 

 upon the English shore, except in the vicinity of Weymouth ; and 

 if the line of elevated strata wliich extends from that part of the 

 coast of Dorsetshire, through the Isle of Purbeck and the Isle of 

 Wight, were continued to the eastward, it would reach the French 

 coast near Gris-nez ; — ^just at the place where the same beds arise, and 

 where it is remarkable their position is likewise very highly inclined. 



Jan. 5. — A notice was read, accompanying some specimens from 

 the Hastings Formation, with a copy of a work on the fossils of 

 Tilgate Forest; by G. Mantell, Esq. F.R., L. and G.S.,— in a letter 

 to R. I. Murchison, Esq. Sec. G.S., F.R.S. &c. 



The author states that his principal object in the present volume, 

 is to give a correct and extended view of that division of the 

 Hastings Sands, distinguished by him in the strata of Tilgate Forest, 

 the relations of which he illustrates by the section of a quarry at 

 Pounceford, where the Ashburnham limestone with bivalves, &c. is 

 seen overlying sandstone and calciferous grit (Tilgate stone). 



A recapitulation of the animal and vegetable remains (in which 

 the author particularly notices that gigantic Saurian the Iguanodon) 

 shows the vast preponderance of land and freshwater exuviae in 

 the Hastings strata over those of marine origin ; a circumstance in 

 strict accordance with what is now constantly occurring in all deltas 

 and estuaries of great rivers.— A description is given in the con- 

 cluding chapter of the work, of the probable condition of the country 

 anterior to the epoch of this deposit. 



The reading of a paper was commenced, entitled " On the coal- 

 field of Brora, in Sutherlandshire, North Britain, and upon some 

 other secondary deposits of the North of Scotland;" by R.I. Mur- 

 chison, Esq. Sec. G.S., F.R.S. &c. 



ASTRONOMICAL SOCIETY. 



Dec. 8. — There was read a letter from Mons. Flaugergues, of 

 the observatory at Viviers, on a Comet discovered there March 

 29th, 1826. M. Gambart, of Marseilles, had informed M. Flau- 

 gergues, that he had discovered, on the 20th of March, a comet, 

 which shortly afterwards moved to the constellation Taurus. — 

 M. F. on looking for that comet, perceived under the left arm of 

 Orion, a white round nebulosity, scarcely visible, which he sup- 

 posed 



