316 CLAY GENUS. Geognojlic Situation. It is found in the vicinity of pfeudo volcanos, and is fuppofed by Werner to be the alhes of coal, which have been walhed down into the lower grounds, and depofited in a regular form. This opinion will be illuftrated and explained in the geognofie. Geographic Situation. Has been hitherto found only in Bohemia. Obfcrvdtiom. Brochant has followed feveral of the German- mi neralogies in confidering the foffil of Menil Mon- tant near Paris as identicalWith the polier flate of ( Werner. It differs from it, however, not only m ory&ognoftic, but in geognoftic characters*. * Wc hare to expert from DaubilTon, the only Frenchman who has fludied the Wernerian geognofie, an account of the intereft- ing country in the vicinity of Paris. The occurrence of the pecu liar foffil, errsneoufiy called polier flate, with its imbedded tuberofc femi-opal, the fuperincumbent gyps, containing remains of quadru peds, (hew that the rocks in that quarter conflitute a peculiar formation, different from any defcribed by Werner. -It is pro bably newer than the neweft fliitz trap, and nearly cotempora- heous with the Wehrauer formation of limeftonc and ironfl« l,e > which lies over alluvial land.