350 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 19, 



well was excavated, beginning in the "grotto-stones" (III. b.) and 

 reaching, at the depth of 70 feet, the bed with N. planulatus, below 

 which water was obtained. There seems to be an average thickness 

 of about 100 feet of strata between the two nummulite-beds and II. 6. 

 and IV. Table XII., but it is very variable. It may be well to re- 

 mark here, that all the fossils figured by Burtin in his ' Oryctogra- 

 phie de Bruxelles,' 1784, were obtained within these limits, or be- 

 tween the gravel containing N. Icevigatus and the continuous bands 

 of rock with N. planulatus"^ . 



In the lowest part of the suburbs of Brussels, near the Pont 

 Leopold, several wells have been sunk, at about 20 J metres or 67 

 English feet above the level of the sea. They passed, first, through 

 alternations of clay and sand {N. planulatus or Ypresien division ?), 

 continuing to the depth of 50 metres, or 165 feet, below which they 

 came to a mass of clay (London clay proper ?, see Section, fig. 8, 

 p. 336), with a thickness of from 20 to 30 metres {^^ to 100 En- 

 glish feet). About 200 feet below the level of the sea they reached 

 the White Chalk with flints, there being, as usual, a parting layer 

 between the tertiary and secondary series containing rolled flints with 

 a green coating. The exact age of the beds here pierced I could not 

 ascertain, as no fossils had been collected. 



Before concluding my remarks on the environs of Brussels, I have 

 thought it useful to insert a list or synoptical Table of the organic 

 remains which have been mentioned in the preceding pages, distin- 

 guishing those found in the Laeken beds as an *' upper" division, 

 and those occurring in strata below (Upper and Lower Brussels Sands), 

 as a "lower " division, but not including the Nummulites planulatus 

 rock. In the same Table I have introduced (as mentioned p. 331) 

 the fossils from the Hill of Cassel, divided in like manner into — 1st, 

 those above the level of the stratum abounding in N. Icevigatus, and 

 2ndly, those below. I was not able in either of these districts to ob- 

 tain suflicient information respecting the division containing N. planu- 

 latus, to add a separate column for its characteristic organic remains. 



For the Brussels lists I am indebted chiefly to Capt. Le Hon, who 

 enabled me to compare a large number of his species with British 

 fossils. The Cassel shells were collected by myself, and named, as 

 already stated, with the aid of MM. Nyst, Morris, and others. 



The last column indicates the localities where the same species 

 occur in England or France. In cases where I was acquainted with 

 an English locality I have not inserted " Calc. gross.," Mr. Prest- 

 wich having shown the close aflinity between the fossil fauna of Bar- 

 ton and Bracklesham and that of the Calcaire grassier, including 

 the sables moyens as its upper division. 



* Mr. T. Rupert Jones informs me that the Nummulite figured as iV. elegans in 

 the * Mineral Conchology ' from specimens marked *' Emsworth, near Chichester," 

 and which Mr. J. de C. Sowerby has kindly permitted him to examine, is (as sug- 

 gested by M. d'Archiac, * Hist. Prog. Geol.' vol. iii.) undoubtedly the N. planvJa- 

 tus of continental geologists. It is probable, therefore, that in that part of Eng- 

 land where the Bracklesham beds with A^. lavigatus are so largely developed, 

 strata characterized by N. planulatun also exist ; and it is highly desirable that 

 their relative position should be carefully studied. 



