754 



MICROSCOPIC GEOLOGY. 



distinctly exhibited elsewhere. Valuable information may often 

 be obtained, too, by treating the ash of an ordinary Coal-fire in the 



Fig. 403. 



f -K 



Microscopic Organisms in Levant Mud : — A, d, siliceous spicules 

 of Tethya; b, h, spicules of Geodia; c, Sponge-spicule (unknown); 

 e, calcareous spicule of Grantia; f, g, m, o, portions of calcareous 

 skeleton of Bchinodermata ; h, i, calcareous spicule of Gorgonia; 

 k, l, n, siliceous spicules of Halichondria ; p, portion of prismatic 

 layer of shell of Pinna. 



