POSSIL CEPHALOPODS. 



303 



such representatives of the order as the cuttle-fish or 

 octopus, and can readily understand why the order is 

 named Cephalopoda^ because of the arrangement of the 

 arms or feet, or whatever we like to call them, around 

 the head. A few members of the order have their 

 hard structures or shells outside their bodies — as the 

 Nautilus, for instance ; but the majority of them have 

 the solid parts inside, 

 which are called "cuttle- 

 bones," "pens," etc. In the 

 modern seas the shelled 

 Cephalopoda (such as the 

 Nautilus) are exceedingly 

 rare, and the cuttle-fishes 

 both abundant and widely 

 dispersed. In the seas of 

 the Palaeozoic epoch the 

 reverse of this was the 

 case — the Nautilus family 

 abounded ; the cuttle- 

 fishes had not come into Fig. 301. -Portion of 7'«rr//.V^. 



existence. All the Cephalopoda are carnivorous in their 

 habits now, and there is every reason to believe they 

 were always so. 



We may practically divide the Cephalopoda into 

 two divisions, for the benefit of the geological student 

 anxious to be acquainted with the fossil remains of 

 each group. First, there are those possessed of shells, 

 such as the Nautilus and Ammonite family; and 



