154 GUIDE TO THE FOSSIL INVEETEBEATE ANIMALS. 



Gallery obscure the water and protect the animal in its flight from 

 'aMe-case enemy. A paint made from this ink is called sepia, after 

 1. the Latin name of the cuttle-fish. The ink-bag is often 

 found in these fossils, and its contents can still be used as a 

 paint. Behind the body-chamber are seen the phragmocone 

 and the guard, and stretching along the sides of the whole 

 shell are expansions of the mantle, forming fins. Belemnites 



Fig. 84. — Eestoration of the animal and shell of belemnites. a, back 

 view ; b, front or under view. (After d'Orbigny.) 



having this general structure and a solid guard lived to the 

 close of the Cretaceous Epoch, when they disappeared. 



Whereas the Ammonites left no descendants, the 

 belemnites appear to have become changed into other forms. 

 One of these, Belosejoia, is found in the Eocene London Clay 

 Table-case (Fig. 85 d). Here the guard has become reduced in size, and 

 the septa stretch in an upward curve from the apex of the 

 shell (corresponding to the belemnite phragmocone) to the 

 front of the pro-ostracum. They are numerous and close 

 together. This form leads to the ordinary Sepia or cuttle- 

 fish, of which two glass models are shown. The shell of this 



