103 



M. Oustalet observes that from these fossils, and a comparison 

 of their species with those found in the strata of CEningen and 

 Radoboj, combined with the study of the fossil flora of these 

 strata, and those of other Swiss and German locaHties, Professor 

 Heer was enabled to form most interesting conclusions on the 

 climate and conditions of life prevailing at that era of the 

 Tertiary period in different countries of central Europe. 



Of the fossil species from the marls of Aix, .Dr. Heer 

 observes that nine have been found at Radoboj, and four at 

 CEningen, that is to say, that twice as many species are found 

 at Radoboj in common Avith Aix than at CEningen, although this 

 last locality is much nearer Provence, and possesses a much 

 richer fauna, and consequently oflers many more points of 

 comparison. Even those species which are not common to both 

 Radoboj and Aix, but are confined to the last locality, are most 

 intimately connected with those of the former. 



At the time at which Dr. Heer was writing, the exact 

 geological position of the gypseous marls of Aix had not been 

 determined, but according to M. Oustalet they were regarded as 

 contemporary with those of Montmartre belonging to the 

 Ligurian or upper Eocene. 



From his study of the fossil insects of these marls Dr. Heer 

 Avas of opinion that their geological position should have been 

 somewhat higlier up nearer the marls of Radoboj in the Miocene 

 formation. Dr. Heer's conclusions, derived almost solely from a 

 study of the fossil insects of the district, have since been to a 

 great extent confirmed by the majority of geologists Avho have 

 subsequently studied this formation, and although the strata 

 have not been referred to the same periods as the marls of 

 Radoboj, they have been placed higher up, near to them at the 

 base of the Miocene period, almost on a level with the sandstone 

 grit of Fontainebleau. * 



M. Marcel de Serres stated, as I have before observed, that 

 the majority of the fossil insects of Aix belonged to existinc^ 



