314 THE OCEAN WORLD. 
of the sea with the undulations of a serpent, so that among sailors 
they have gained the appellation of sea-serpents. These long living 
trains abound in the Mediterranean, principally towards the African 
coast and in the equatorial seas, and they are often met with on the 
south-western shores of Ireland. They are inhabitants of the open 
sea, and live immersed at considerable depths ; but when the nights 
are calm they show themselves on the surface. As they spread 
126.—Phosphorescent chain of Salpas on the surface of the sea. 
themselves abroad, and set aglow their strong phosphorescent light, 
they resemble long ribbons of fire, unrolling their long waving lines 
in spite of the waves, as in Fig. 126. What wonders they see who 
go down into the great deep! What sights are reserved for the 
navigator who traverses the semi-tropical seas during the silence of 
night ! 
When a chain of Salpa is drawn from the water, the zooid forms 
separate, and they can no longer be made to adhere. The social 
bond has been dissolved. 
Salpz are sometimes met with, isolated and solitary, whose 
exterior conformation differs much from that which is proper to the 
