140 UTILIZATION OP MINUTE LIFE. 



Its bone, which supports the soft parts of the 

 animal's body, is employed to polish ivory and bone 

 objects, to prepare tooth-powder, and for a host of 

 minor uses. It is known in the shops as " Cuttle- 

 bone/' or when powdered as " Pounce." It is fre- 

 quently hung in the cages of Canary birds, who 

 clean and sharpen their beaks by pecking at it. 

 This bone exists in other animals of this group : in 

 Loligo vulgaris (the common Calamary) it is almost 

 transparent, and sloped somewhat like a pen, whence 

 this and other allied species are sometimes called 

 Pen-fish. Loligo iwlgaris is common on our coasts. 

 The colour of its almost transparent greenish body 

 changes at intervals, and adapts itself to that of the 

 water it inhabits. In all the so-called naked* 

 Cephalopoda the colour of the skin is highly 

 changeable, showing spots which brighten and fade 

 with a rapidity superior to the cuticular changes of 

 the chameleon ; a faculty which they owe to a very 

 remarkable cuticular tissue, which has often engaged 

 the attention of anatomists. 



Hardly any sea is without some species of naked 

 Cephalopoda ; their food consists principally of fish 

 and Crustacea, but they are very voracious, and will 

 devour almost any kind of animal matter. Their 

 flesh, especially that of the tentacles, is edible, and 



* To distinguish them from those possessed of shells (Nautilus, 

 etc.) 



