GEOLOGY, 311 



ed various questions as to the Feldspars in Crystalline Rocks, 

 their Chemical Composition and Microscopic Characters ; 

 and were followed by T. Sterry Hunt on the Constitution 

 of the Plagioclase Feldspars ; while Jannetaz treated of the 

 Geological Importance of the Propagation of Heat in Rocks 

 considered with reference to their Structure and their Ori- 

 gin. T. Sterry Hunt then gave a description of the Great 

 Groups of Crystalline Stratified Rocks found in North Amer- 

 ica, including Laurentian, Norian, Huronian, Montalban, and 

 Taconian, and compared them with similar groups in Europe. 

 He was followed by Selwyn on the same subject. Szabo dis- 

 cussed the Eruptive Tertiary Rocks of Hungary, examining 

 the question whether the Mineral Composition can serve to 

 show the Ao-es of such Rocks. Velain contributed an ac- 

 count of the Trachytes of Reunion Island, and Ribeiro one 

 of the Tertiary Basalts of Portugal. 



In the sixth and last session of the Congress, on the 4th of 

 September, a communication by Bourjot was presented on 

 the Supposed Eruptive Limestones of Algeria ; and one on 

 some Glacial Phenomena of the great Lake District of North 

 America, by Chamberlin ; while Fuchs resumed the views of 

 several members of the Congress on the System of Coloring 

 Geological Maps. The president then announced the de- 

 cision of the Council that the acts of the Congress are to be 

 published in a volume under the direction of the secretaries, 

 the cost being generously defrayed by the national govern- 

 ment. A second International Congress will be held at 

 Bologna, in Italy, in October, 1881, under the honorary pres- 

 idency of Sella, President of the Academia dei Lincei of 

 Rome, and a Local Committee of ten Italian geologists has 

 been named, charged with the organization of the Congress, 

 of whom Professor Capellini, of Bologna, will probably act 

 as secretary. The government of the King of Italy, through 

 its ambassador at Paris, at once promised its high patron- 

 age to the future Congress, and the municipality of Bologna 

 sent a message of welcome. 



The work of the next Congress is referred to two Interna- 

 tional Committees ; the first of which will be charged with 

 the Unification "Des Figures Geologiques," that is to say, 

 of all colors or signs employed on geological maps and plans. 

 The second is charged with the Unification of Geological No- 



