Cephalopoda — Dibranchtata . 



13 



silvery, outer coat. It discharges its contents through the anus, ^^^^}^- 

 which opens near the base of the funnel. The inky fluid i 



GALLERY 



mulated in this reservoir can be discharged at will by the animal, vil. 

 and serves to cloud the water for yards around, thus concealing its Wall-cases 

 retreat, and so enabling it to evade its pursuers. Many examples ^ * 

 of fossil Dibranchiata are exhibited in the cases, in which the ink- 

 bag is still preserved in siM. 



la. 



Fig. 30. 



-Ommastrephes sagittatus, Lamk. (British), a, the animal ; b, the 

 internal shell or pen. 



The dried ink-bags of cuttle-fishes and squids are regularly 

 collected and prepared by artists' colourmen to form the pigment 

 known as "sepia." The Chinese and Japanese had probably used 

 it both as a pigment and as a writing fluid long ages before it 

 was known in England ; and it was so used in Greece in the time 

 of Cicero, B.C. 106. 



From their extreme delicacy, the internal shells of Dibranchiata 

 Cephalopods are but seldom preserved in museums. The solid 

 guards of the Belemnites (Fig. 31) are very abundant in a fossil 

 state. The internal pens of Teuthidse are more rare, but occur in 

 the Cretaceous beds of the Lebanon (Fig. 32) ; in the Lithographic 



