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ledge of the external form of mining districts, though not 

 without its value in the search for useful minerals, is never- 

 theless not altogether to be relied upon, as phenomena occur 

 within a short distance to support, as well as contradict, 

 known rules. The Professor first explains the peculiarities 

 of granitic structure, together with the structure of slate 

 rocks, and next points out the peculiarity of classes and 

 formations, and the relations of these amongst themselves, 

 together with their subordinate members, as porphyries, 

 syenites, greenstones, and limestones. The paper is to be 

 continued, and as the part which has appeared scarcely dif- 

 fers from the geognostical views of Professor Jameson, pro- 

 posed to the Wernerian Society in 1813, we need not dwell 

 on them in this place. 



The next paper is on Danish Oyster Beds, by M. Kroyer, 

 from which we learn that oyster beds are not essentially 

 elevated portions of submarine land, or rocks. Oysters at- 

 tach themselves by their valves to loam, sand, or mud, 

 either of which answers equally well, only on such banks 

 the oysters must necessarily lie loosely, or merely attach 

 themselves to each other's shells, thus appearing in clusters. 

 We must therefore be prepared to tolerate this incon- 

 venience, in such oysters as may, out of consideration for 

 the good people of Calcutta, establish a settlement within an 

 available distance of the city. 



The third article is a short notice by M. H. von Meyer, 

 of a Fossil Passerine Bird, about the size of a lark, in a slate 

 supposed to be of the age of the chalk, which is the more 

 valuable, perhaps, as M. Meyer himself had long doubted 

 the existence of birds in formations antecedent to the ter- 

 tiary series, having referred many of the so-called bones 

 of fossil birds to Pterodactyles, in whose bones M. v. 

 Meyer discovered air cells as in those of birds. 



The fourth article from Dr. Holland's work on the Influ- 

 ence of Weather on Disease, is interesting, but too long to 

 quote, nor do we see any thing in it either new or curious to 



