M. Alcide d'Orbigny on Living and Fossil Molluscs. 57 



The strict resemblance of this specimen, both in physical and che- 

 mical properties, to the many recorded examples of meteoric iron, 

 leave no doubt regarding its nature. 



Its vesicular surface indicates a state of fusion, which the power 

 of the native furnaces of this country is quite inadequate to produce 

 in iron of such toughness and malleability ; and, moreover, its con- 

 stituent nickel, so near the average proportion of five percent., points 

 distinctively to its meteoric origin. 



Like the Siberian meteoric iron, described by Pallas, when heated 

 strongly, it became brittle, refused to extend under the hammer, and 

 broke into grains ; and, like the Brazilian specimen described in the 

 Philosophical Transactions, it gave abundance of sparks when struck 

 with a steel hammer. 



M. Alcide d'Orbigny on Living and Fossil Molluscs. 



Among the zoologists whose labours have contributed 

 most to increase our acquaintance with the relations which 

 ancient faunas bear to the animals of the present epoch, M. 

 Alcide d'Orbigny occupies a place in the first rank. This 

 skilful naturalist has published, within these few years back, 

 a series of works,* which, taken together, may be said to 

 form an epoch in the history of zoology and palaeontology. 

 Studying each natural group of the great and important class 

 of mollusca in succession, and comparing these animals in 

 the different geological periods, and in the existing world, 

 he has reached results of the highest interest. We shall 

 here explain the most important of these, selecting more 

 especially such of them as are connected with those prin- 

 ciples of palaeontology which we have often had occasion to 

 lay before our readers. 



We shall first bring forward the following considerations 

 on the geographical distribution of living molluscs. No one 



• M. d'Orbigny "s works of which we chiefly wish to speak, are his Paleon- 

 tologie Fraifxiue (already consisting of upwards of 170 livraisons,) which is de- 

 voted to the fossil molluscs of Prance ; his Paleontologic Etrangere, the companion 

 of the former; his History of Living and Fossil Molluscs, a work which will 

 be of immense utility, if it be completed. He promises, besides, a Cours de 

 Palcuntologie Oenerale et Appliquie. 



