I 
602 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 sulj^hate ; 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 origiDal 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. 
