MICROSCOPIC OBJECTS. 97 



Fig. 193. Section of Oolitic Argillaceous Shale from Arica, 

 Peru, x40. 



This rock belongs to the oolitic system, so called from 

 most of the rocks having the appearance of minute round 

 bodies similar to the eggs of fish, as in the figure, this appear- 

 ance arising from the globular deposit of carbonate of lime 

 around grains of sand. 



It belongs to the sedimentary formations. 



Fig. 194. Section of Marble taken from the Temple of Diana 

 at Ephesus, x 20. 



The beautiful appearance of this rock under polarized light 

 can scarcely be appreciated from the drawing, as the several 

 colours of the various particles are necessarily wanting. 



It belongs to the metamorphic rocks. 



