144 The Under-Water World 



disturbed or at rest they resolve them- 

 selves into mere blobs of jelly, but when 

 foraging for food and fully expanded 

 they resemble a garden slug ornamented 

 with candles, antlers and flowers a won- 

 derful medley of bizarre forms. The 

 gills are frequently modified to harmonise 

 with the animal's surroundings. Thus 

 the Sea Lemon has the gills so coloured 

 and arranged that they blend with the 

 creature's favourite food, the ' bread- 

 crumb " sponge, whilst those of the Grey 

 Sea Slug of our shores are indistin- 

 guishable when amongst the waving 

 tentacles the sea-anemones upon which 

 it feeds. 



The Octopus, Cuttle-fish and their allies 

 belong to a highly organised group of 

 molluscs the Cephalopods the mem- 

 bers of which, known in popular language 

 as devil-fish, have made the public flesh 

 creep from the earliest times. Although 

 many authors have drawn upon their 



