io8 STUDIES IN INSECT LIFE, ETC. 



and tentacles, act as sensitive outposts. Many 

 deep-sea animals have become sightless ; others, 

 as they approach the bottom, develop larger and 

 more efficient eyes, sometimes standing out from 

 their heads like binoculars, or even borne on the 

 ends of stalks, as is the case in some of the eight- 

 armed cephalopods (squids), 'and the larvae of 

 certain fishes. 



Many of the fish are black, and what is more 

 remarkable, they are dark inside as well as out. 

 The cavity of the mouth and that of the body are 

 alike lined by tissues of the blackest hue. Others 

 are almost transparent, and indeed one can easily 

 read print through the body of a Leptocephalus, 

 the larva of the common eel, which is so trans- 

 parent that one would not be able to see it in a 

 dish but for the presence of the pigment in its 

 eyes. But these larvae pass up to the surface at 

 a very early stage, and their transparency may 

 be due to the fact that they are destined to a 

 surface life. Many other forms are, however, 

 very gorgeously coloured, and yet as far as we 

 know " their glory is concealed/' for there is no 

 light and often no eye to note the brilliant blues 

 the oranges, the greens and reds, the violets and 

 purples which deck their bodies. Perhaps it 



