394 Geological Society : — 



bones and teeth from the Bone-bed which occurs between the Trias 

 and the Lias. Mr. Dennis considered that some of these fossils pre- 

 sented mammalian structure under the microscope. Among the 

 specimens from the Lyme Regis bone-bed. Prof. Owen determined 

 the remains of Lepidotvs and Saurichthys, and of another fish, Pla- 

 codus, which had not previously been recognized among British 

 fossils. 



2. " On the Valenciennes Coal-basin." By M. Laurent. In a 

 Letter to A. Tylor, Esq., F.G.S. 



This communication referred to the works in the coal-basin of the 

 departments of the "Nord" and the "Pas de Calais," on the pro- 

 longation of the Belgian basin of Mons. At the end of the last 

 century, France in the north possessed only the mines of Auzin, 

 which were first worked in 1716. This state of things lasted until 

 1832, when the workings only extended to Denain. In 1839, the 

 concessions of Douchy, Bruelle, Vicoigne, Auiche, Agincourt, and 

 Thioncelles were made. The works of research went on until 1841, 

 at which period the adventurers, discouraged by the numerous fruit- 

 less attempts made in the supposed direction of the basin towards 

 Arras, abandoned them. Six years later, the works undertaken 

 towards the north-west of Douai, in the direction of the present 

 concessions of the " Pas de Calais," indicated the true direction of 

 the coal-basin ; and down to 1854, numerous trial-sinkings, of 

 which many passed through the coal, led to the establishment of 

 nine new concessions ; and a tenth, on the border of the basin, is in 

 progress. Two more also have been made this year (1855), one to 

 the north of Douai, the other to the north of Bethune, above 

 Cheques, where they suppose that the bands of dry cocd (faisceau 

 maigre) end, the basin beyond this place becoming narrower, and 

 representing only the seams of caking coal in all the concessions to 

 the west. 



Many works have, moreover, been undertaken in the course of 

 the last three years, in search of a widening of the basin by the 

 series of the seams of caking coal, and of an extension of the dry- 

 coal band, which disappears at Choques. With the exception of 

 those made by the " Vendin Company," these sinkings have as yet 

 given only negative results. 



In all the sinkings which have been made from Valenciennes to 

 the furthest of these researches, the Chalk forms the (inort ter- 

 rain) " head," and with a varying thickness. As far as Aire the 

 Chalk alone forms the rock which has to be passed through before 

 reaching the Coal, from which it is separated by a bed of greensand 

 from 1 to 3 metres in thickness, known by the name of " tourtia." 

 On the north of Aire it is, in addition, covered up by tertiary depo- 

 sits, alternations of sands and clays, with a thickness in places of 

 100 to 150 metres, and which render it necessary to line the sink- 

 ings as the work advances. This formation is found even in Bel- 

 gium, at St. Ghislain, near Mons, with a thickness of 60 metres. 

 The average thickness of the overlying beds is 140 metres. It sel- 

 dom exceeds 180 metres, and was found to be ordy 85 metres at 



