EHIZOPODA. 25 



numerous in the latter, extensive beds of which 

 are in many districts made up of Httle else than 

 the shells of Rotalia, Spirulina, and Textidaria. 



But it is in the formations of the Tertiary 

 period that this group may be said to have at- 

 tained its greatest development. It is here we 

 first meet with the widely distributed Kumviulites, 

 whose size, compared with that of any Forami- 

 nlfera which have preceded them, must be consi- 

 dered as gigantic. They are chiefly characteristic 

 of the Middle Eocene ; and it has been proposed 

 by some geologists to divide this formation into 

 three sections, each being distinguished by a se- 

 parate form of Nummulite. The extent to which 

 some of these strata prevail has been thus indi- 

 cated by Sir Charles Lyell. 



" The Nummulitic formation, with its charac- 

 teristic fossils, plays a far more conspicuous part 

 than any other tertiary group in the solid frame- 

 work of the earth's crust, whether in Europe, 

 Asia, or Africa. It often attains a thickness of 

 many thousand feet, and extends from the Alps to 

 the Carpathians, and is in full force in the North 

 of Africa, as, for example, in Algeria or Morocco. 

 It has also been traced from Egypt, where it was 

 largely quarried of old for the building of the 

 Pyramids, into Asia Minor, and across Persia, by 

 Bagdad, to the mouths of the Indus. It occurs 

 not only in Cutch, but in the mountain ranges 

 which separate Scinde from Persia, and which 

 form the passes leading to Caboul; and it has 

 been followed still farther eastward into India, as 

 far as Eastern Bengal and the frontiers of China." 



It has been shown by Dr. Carpenter that the 

 Nummulitic limestone of some districts contains 



