262 UTILIZATION OF MINUTE LIFE. 



tertiary limestones, furnish us with examples in 

 every part of the world." 



Traces more or less abundant of Foraminifera 

 are to be found in the calcareous rocks of nearly 

 every geological period ; but it is towards the end 

 of the secondary and at the commencement of the 

 tertiary period, that the development of this group 

 of fossils seems to have attained its maximum. 



" Although there can be no reasonable doubt/' 

 says Dr. Carpenter, "that the formation of chalk is 

 partly due to the disintegration of corals and larger 

 shells, yet it cannot be questioned that in many 

 localities a very large proportion of its mass has 

 been formed by the slow accumulation of foramini- 

 ferous shells." 



But the calcareous bed of the tertiary forma- 

 tions, known as Nummulite limestone (on account of 

 the enormous quantity of Nummulite shells larger 

 Foraminifera which it contains), is perhaps more 

 interesting still. This Nummulitic limestone can 

 be traced from the Pyrenees, through the Alps and 

 Appenines, into Asia Minor, and further, through 

 Northern Africa and Egypt, into Arabia, Persia, 

 and Northern India ; and thence, in all probability, 

 through Thibet and China to the Pacific, covering 

 very extensive areas, and attaining a thickness in 

 some places of many thousand feet. Another tract 

 of this remarkable strata is found in North America. 



