162 Account of the Proceedings of the 



stones and slates above the Chemung group, inclusive, are all referred 

 to the Devonian series. The characters common to the Devonian 

 fauna of Europe and America are considered to be the appearance of 

 the ganoid fishes with great plaques or scales, and the genera Gonia- 

 titcs. Nautilus, Pentremites, and Productus. 



Above these American rocks come the limestones referred to the 

 carboniferous limestones of Europe, and M. de Verneuil considers 

 this division as well characterised in both continents ; and it is re- 

 marked that the Trilobites, decreasing in a parallel manner in both 

 countries, finally end with the small species of Phillipsia in the car- 

 boniferous limestones. The memoir of M. de Verneuil, of which the 

 above is a very brief sketch, contains much detail, and terminates 

 with remarks on the palaeozoic fossils common to America and 

 Europe, and on their distribution. 



In a memoir on the mineral and chemical composition of the rocks 

 of the Vosges, M. Achille Delesse remarks on the passage of the dif- 

 ferent igneous rocks into each other. M. Delesse observes that many 

 minerals, even those widely spread and forming important portions 

 of rocks, are but little known, and he points out the felspar family, 

 though it forms fifty percent, of the crust of the globe, as being one 

 the species of which are Httle understood. Their chemical proper- 

 ties are nearly identical, and their composition has reference to a 

 common law ; they all contain the same radical bases, in such pro- 

 portion that the quantities of oxygen are as 1 to 3, and the different 

 felspars are only saturations of these radical bases with silica. Hence 

 the difficulty of determining the different felspars, though they be- 

 long to an easily-distinguished natural family. 



After taking a brief view of the foi'mation of the stratified, M. De- 

 lesse proceeds to examine that of the unstratified rocks, and their 

 igneous origin, glancing at the original fluidity of the earth, its con- 

 sequences, and the metamorphism of rocks. Proceeding to the classi- 

 fication of the non-stratified rocks, he points out that too much im- 

 portance has been assigned to their physical characters, and too little 

 value given to their chemical composition, and that it is highly de- 

 sirable researches in chemical mineralogy should accompany the geo- 

 logical study of the non-stratified rocks. He adds, that these re- 

 searches in chemical mineralogy should be carried on with the rocks 

 in place, inasmuch as the chemical geologist will not otherwise be 

 enabled to observe all that is required. In this manner M. Delesse 

 studied the non-stratified rocks of the Vosges, carefully separating 

 the isolated minerals from the main mass and subsequently experi- 

 menting upon them, and as carefully also examining the main mass 

 or base of the locks. The crystals in the Belfahy porphyry were 

 found to be a variety of labradorite. Augite is another mineral found 

 in this porphyry, one of those termed also Melaphyre. Its base or 

 paste contained water chemically combined, as in the crystals of fel- 

 spar, and M. Delesse I'efers to the views of M. Scheerer on this sub- 



