SHALLOW-WATER FAUNA. 49 



a hole in the rocks and waits patiently until the 

 new shell has grown. 



The animals included under the popular names 

 of Cuttlefishes, Squids and Octopuses are also 

 capable of crawling about among the rocks by 

 their long feeler-like arms ; but they are in the 

 habit, as well, of making prolonged 

 journeys through the water, by 

 pumping the sea-water through a 

 tubular siphon situated on the 

 under side of their bodies. These 

 animals possess in such a remark- 

 able degree the power of changing 

 colour that they might be called 

 the Chamaeleons of the sea. As 

 'they pass slowly through the water 

 from one part of the coast to another 

 the colour of the skin changes so as 

 to resemble the colour of the rocks 

 or weeds which are below them. 

 These changes are brought about 

 by numerous little bladders in the 

 skin which are filled with different 

 coloured fluids, and are worked by 

 a complicated system of muscles 

 under the control of special nerves 

 from the brain. When the colour 

 blue is predominant, it is found that all the 

 bladders containing blue fluids are dilated, the 

 others being constricted ; when the colour is red 

 the red bladders only are dilated, and so on; 

 and as the nervous response to the colour of the 

 rocks perceived by the eye is practically in- 

 stantaneous, the change in the general colour of 

 D 



