EXTINCT ANi:\IALS 



amination of the animal of Nautilus), and be- 

 longed to the class Cephalopoda of the great 

 group Mollusca. The Molluscs include, besides 

 these, the whelks, snails, mussels, clams and 

 oysters. 



Fig. 196. — Bclemnitcs hastatus from the Oxford Clay (Jurassic). 

 The left-hand figure represents a specimen cut in half and 

 shows tlie conical cavity or phragmacone (rudimentary 

 chambered shell). The right-hand figure is the " thunder- 

 bolt " as usually found. 



A celebrated fossil which is the internal shell 

 or " pen " of a kind of cuttle-fish is that known 

 bythename "Belemnite"(Fig. 196). Thesefossils 

 are called " thunder-bolts " in some parts of 

 England, where they are sufficiently common in 

 the clay and shale to attract attention. They 



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