the Subject of ^^ Eozoon.'' 391 



complete as to prevent our coming to any other conclusion 

 than that they were residual bodies, and not concretions, infil- 

 trations, or crystallizations. As to their being portions of 

 an organism, the idea would not bear any serious considera- 

 tion. Wherever the changes had taken place, a carbacid 

 mineral (calcite, or dolomite) had replaced the chrysotile, 

 flocculite, and metaxite ; so that it became evident that we 

 had before us the results of chemical changes analogous to 

 certain kinds of pseudomorphosis occurring among minerals. 



Not only does serpentine present unmistakable evidences of 

 the above changes, but certain of them have occurred to us in 

 other silacid minerals, as malacolite and Wollastonite. Agglo- 

 merations of minute crystals of these minerals are common in 

 certain so-called primary limestones (notably at Aker in Sweden, 

 Amity in New York, and in Ceylon), so reduced by solvent or 

 chemical action (the component crystals still retaining in many 

 cases their original angles, edges, and planes) as to assume the 

 exact forms of the " eozoonal canal-system " in its typical 

 condition, and showing clearly their residual character, also 

 the replacement of their lost or eroded portions by the calcite 

 or dolomite in which they are imbedded. 



A more important discovery we had not anticipated. It 

 opens out a wide field of research in chemical geology, an 

 insight into which, however, has been afibrded by the illus- 

 trious Bischof. Of late the subject has been frequently under 

 our consideration. It is well known that certain rocks are 

 not in their original chemical condition : the changes in 

 serpentine render it extremely probable that ophite (a silo- 

 carbacid rock) is a chemically changed or methylotic product, 

 that the Tyree, Aker, and other crystalline marbles were ori- 

 ginally silacid masses, and possibly that much of the so-called 

 " limestones " occurring in the Laurentians of Canada were, 

 in Archsean periods, silacid members of true gneisses, dicTi'ites, 

 and otlier related rocks *. We need not dwell any longer on 

 this subject ; suffice it to say that we are pursuing a number 

 of researches in connexion with it. We have been favoured 

 with specimens by Mr. F. R. Mallet, of the Indian Geological 

 Survey, discovered by himself in dolomitic bands intersecting 

 transversely beds of gneiss at South Mirzapurf, showing typi- 

 cal eozoonal structures beautifully developed through methy- 

 lotic action ; and last summer one of us obtained at the 

 Lizard, Cornwall, aided by the kindness of Mr. Symons, 

 manager of the Poltesco marble-works, a number of speci- 



* See a paper by one of the writers in the ' Geological Magazine ' 

 for January 1872. 



t Records of the Geological Survey of India, No. 1, 1872. 



