502 



THE GEOLOGIST. 



of carbonate of baryta ; carbonate of iron, and carbonate of zinc in 

 the form of calcite, and of aragonite ; carbonate of baryta in the form 

 of the sulphate ; and carbonate of iron, and the black oxide of iron in 

 the form of gypsum, in which latter two instances there has been a 

 complete replacement of the original constituents, but the crystalline 

 form is perfectly preserved. 



Dr. Kurz read a paper on the variegated sandstone of Germany, 

 the chief point being whether certain beds which have been looked 

 upon as deposited one over the other, were not really contemporaneous, 

 but formed under different physical conditions. After which Dr. Mohr 

 made some observations on the origin of limestone. He thinks shells 

 and corals abstract their calcareous substance from the gypsum dissolved 

 in the sea water, and that the carbonate of lime brought into the sea by 

 rivers is altered to the sulphate by the sulphuretted compounds given 

 off from decaying organic bodies. Dr. Redenbacher described in 

 detail a new species of Pterodactyle from Solenhofen, and then Dr. 

 Otto Buchner read a paper by Haidinger on his views respecting 

 meteors, of which notice is made in the last number of the " Geologist" 



(p. 420). He exhibited the section of an interesting specimen which 

 had a structure similar to that of the Septaria so well known to 

 geologists, and through his kindness I am able to reproduce a print 

 taken from it. 



