222 GENEVA SOCIETY OF PHYSICS AND NATURAL HISTORY. 



also a remarkable leaf and fruit-bearing stem of the Diacontium pertusum. 

 The same member, when on the subject of the investigations of Profes- 

 sor Favre on the hill of Cassina Rizzardi near Como, remarked that the 

 two Tertiary and Quaternary floras north of the Alps are distinctly 

 separated by the Glacial period, while south of the Alps the Pliocene 

 and Quaternary regions fade into each other, the Tertiary flora already pre- 

 senting many of the plants of the present epoch. M. de Candolle like- 

 wise made a detailed report of the work of M. Francis Galton on twins 

 in the human species. 



Prof. A. N. Cazin, of Paris, honorary member of our society, gave an 

 interesting recital, rich in details, of his journey to the island of St. Paul, 

 to observe the transit of Venus. 



Professor Dor, of Berne, made a detailed report of the experiments 

 made under his direction by M. Decker, at the ophthalmological clinic 

 of Berne, on the influence of the trijumeau in certain affections of the 

 cornea. 



M. Fatio described his researches, made conjointly with M. Adore, 

 to determine the moment at which, with us, the winged form of the 

 Phylloxera is produced. It was proved that the event takes place in the 

 middle of July. These gentlemen also discovered a plant-louse, strongly 

 resembling the Fhylloxera, on the leaves of the maple. 



M. Ernest Favre, while distributing a memoir on the Jurassic rocks of 

 the Voirons, entertained the society with the discussions of geologists 

 ou the limits of the Jurassic and Cretaceous periods, and more par- 

 ticularly on the tithonic stratum of cephalopodic and coralline beds. 

 Far from sharing the opinion of the geologists, especially the French, 

 who see a great hiatus between the Oxford beds and the Cretaceous 

 deposits of our Alps, M. Favre adaiits, with the other Swiss and Ger- 

 man geologists, that at least for the Western Alps, and likewise the 

 Voirons, these are all the equivalents of the Jurassic rocks; aud if we are 

 still unable to verify all the fossil iferous levels of the Jurassic basin, it 

 is because the sediment was formed under diflerent conditions, especially 

 with regard to temperatures and currents. Professor Favre proves that 

 by examining, on the spot, the hill of Cassina Eizzardi, near Como, 

 where it was claimed that there were Pliocene shells iu the glacial ter. 

 rains he saw nowhere between Mendrisio and Chiasso that pretended 

 mixture; that the hill in question bears no resemblance to a moraine; 

 and that it is formed from a i^ost-Glacial alluvium. The fossils found 

 there were washed down by streams which drifted the rolling stones in 

 which these fossils are imbedded. M. Favre likewise showed us speci- 

 mens of the mineral known as the sapphire of the glacier of the Bois, 

 and now classed by M. Spocia with emeralds. 



M. Fol described in the embryos of mole-crickets, before hatching, a 

 larval heart analogous to that of the larva of mollusks. It is a contrac- 

 tile region of the ectoderm on both sides of the body. The same scien- 

 tist gave some interesting details of the zoological laboratories of 

 Naples and Eostock. 



