PLATE XXIV 



THE BELEMNITE AND ITS DESCENDANTS 



Sections through the middle of the shells, all in the same position 

 (after Lang) : 



A, A Belemnite. F, Belemiwtetithis. 



B, Spirulirostra. G, Conoteuthis. 



C, Spirilla. H, Ommastrephes. 



D, Belosepia. I, A squid 



E, Sepia (Common Cuttlefish). 



In all Figs., p.o. is the pro-ostracum ; si., shell siphuncle ; and 

 g., guard. 



The shell wall and septa are represented by thick black lines. 



[Reproduced by permission of the Trustees of the British Museum from their 

 " Guide to the Fossil Invertebrate Animals."] 



