248 



THE WONDERS OF GEOLOGY. 



Lect. III. 



The Nummulite, which is the largest of this order, is of 

 'a lenticular, discoidal form, and varies in size from a mere 

 point, to an inch and a half in diameter. The outer surface 

 is generally smooth, and marked with fine undulating lines. 

 On splitting the shell transversely, it is found to consist of 

 several coils, which are divided into a great many cells or 

 chambers by oblique partitions (Lign. 41, Jig. 1), having 

 no communication with each other. The specimens which 

 I now place before you (Lign. 41), are from the limestone 



LlGN. 41. — NUMMULITES, FROM THE GREAT PYRAMID OF EGYPT. 



{Collected by Dr. George Hall, of Brighton.) 



Fig. 1. Horizontal section of a Nummulite. Figs. 2, 3. Nummulites, with the 

 external plate partially removed. 



which constitutes the foundation rock of the Great Pyramid 

 of Egypt, and of which that structure is in great part com- 

 posed. Strabo alludes to the nummulites of the Pyramids, 

 under the supposition that they are lentils which had been 

 scattered about by the workmen, and had become converted 

 into stone. This polished pebble from Egypt, is a silicified 

 mass of nummulites, the markings on the surface being 



