ANNUAL ADDRESS, MDCCCLXXIII. 37 



rubbed to powder in water, and the lighter particles poured 

 off, a great number of beautiful forms are revealed by the 

 microscope. They consist of foraminifera3 called globi- 

 gerina, sponge spicules, &c. There is an interesting slide 

 of them under the microscopes. 



The close of the chalk period marks the end of the 

 geological division of the secondary epoch and the advent 

 of Tertiary, the lowest member of which is the Eocene 

 group. It was in this period that another grand limestone 

 deposition took place, which extended from the Alps to 

 the Himalayas. It is often found several thousands of feet 

 in thickness, and consists of myriads of a characteristic 

 foraminiferas called nummulites, from their resemblance to 

 a coin. The nummulite resembles in form and size a worn 

 sixpence, although much more convex. Under the micro- 

 scope it is revealed as a many-chambered shell of complex 

 organization. This extent of nummulitic limestone is almost 

 amazing : a band of it, often 1,800 miles in breath, extends 

 from the Alps to China. The Pyramids are built of it. 

 It forms some of the highest mountain ranges of the Alps 

 and Pyrenees. It is found on the Alps at a height of 

 10,000 feet, and forms the summits of the Dent du Midi 

 and Diableretz, whilst in the Himalayan mountains it has 

 been recognized by Dr. Thompson 16,500 feet above the sea. 

 Nor is the profusion of its traces of life less amazing. 

 It may be safely said that much of it is almost entirely 

 made of nummulites. There is a good though small 

 specimen on the table, which shows the nummulitic form 

 very well, and there is also a slide under the microscope 

 showing the structure. 



Whilst this immense area of comparatively recent lime- 

 stone was being formed, what was the condition of those 



