OUR COMMON BRITISH FOSSILS. 



open, reveal the coiled-up ringed shell, wonderfully 

 resembling a snake in such species as Ammonites 

 communis, and still more wonderfully resembling one 

 when they put a " head " on, with 

 eyes in as they sometimes do. 



Zones of Ammonites also occur 

 in the Oolitic rocks, both of Eng- 

 land and Scotland, as those of A. 

 Calloviensis, etc. In Scotland there 

 is an extensive outlying series of 

 Liassic and Oolitic beds, as in 

 Skye, and other islands, and in Sutherlandshire 

 remnants of a vast sheet of Secondary strata which 

 probably once completely covered the Western High- 



Fig. 316. Ammonites 

 varicosiis. 



Fig. 317. Ammonites Cooperi. 



lands, where they have long been removed by de- 

 nudations. In the Oolitic strata of Sutherland an 

 impure coal is worked, as at Brora, and there the 



