ANNIVERSARY ADDRESS OF THE PRESIDENT. CI 



With respect to granites, M. Durocher considers that in the greater 

 number of cases the sohdification of the different constituent elements 

 of the rock took place at nearly the same time, but not so with the 

 porphyries. With respect to the view of water forming an essential 

 part of granites, he infers that, a priori, the quantity must be very 

 small, less than one per cent. By experiment he did not find so 

 much as five thousand-parts of water in granites, felspathic rocks 

 and quartziferous porphyries which were not decomposed. The small 

 quantity of water found in ordinary granites (always excepting those 

 containing talc or chlorite) appears to him to be due to percolation 

 subsequent to their original consolidation, while he admits that many 

 igneous rocks, such as serpentine, diallage rock and others, may have 

 originally contained water as an essential component part. 



During his experiments on the igneous rocks, M. Durocher found 

 carbonate of lime and dolomite in many, these substances being in- 

 visible by means of a lens. With respect to dolomite, he found "0092 

 of it in a granite from Stockholm, 'OOS in a protogyne from the Vallee 

 de I'Agly (Pyrenees Orien tales), "0043 in a petrosilex from Sala 

 (Sweden), '013 from a euphotide of Savoy, "0024 from a basalt of 

 Saint-Flour (Cantal), and •0062 in an olivine lava of Auvergne. From 

 •001 to '018 of carbonate of lime, either pure or slightly magnesi- 

 ferous, was in twenty-five specimens of granitic and other igneous 

 rocks considered original and not due to infiltration. 



M. Pilla, whose loss to science amid the late political events in 

 Italy we have to deplore, communicated a notice on the red ammoni- 

 tiferous limestone of Italy. Having noticed the rocks of the districts 

 of the Lago di Como, of La Spezia and of the mountains of Tuscany, 

 referring to the previous writings of geologists, he infers that the true 

 position of the red ammonitiferous limestone is in the Liassic Jura 

 series, quoting the observations of Von Buch as to the liassic or in- 

 ferior oolitic character of the contained ammonites as showing the age 

 of the beds of the Lago di Como, where, from their mode of occur- 

 rence, they might otherwise be referred to the higher part of the 

 Jurassic series. At La Spezia and in the mountains of Tuscany the 

 red ammonitiferous limestone rests immediately on a dolomite and 

 black limestone, rocks which, by their position and fossils, are con- 

 sidered identical with the dolomite and brown limestone of the valley 

 of Esino, lake of Como, which geologists view as forming part of the 

 lias. The exact equivalent M. Pilla supposes may be the lower part 

 of the oolitic series. 



M. Pomel described a new fossil pachyderm from the basin of the 

 Gironde, named Elotherium magnmn, considered to bear the same 

 relation to the hippopotamus that the tapirs and rhinoceros do to the 

 lophiodon and palseotherium. 



In a memoir on the nummulitic rocks of the departments of the 

 Aude and of the Pyrenees, M. Tallavignes proposes to describe these 

 deposits with reference to the localities named, and not with regard 

 to general classifications. He finds two formations, distinct both in 

 their geological and paleeontological characters. The first contains 

 either new or known tertiary fossils, and the beds are commonly 

 horizontal. To this formation M. Tallavignes assigns the name of 



