284 THE INHABITANTS OF THE SEA. 



sparkling like the purest crystal shines with the liveliest 

 colours, red, yellow, or azure. Some inhabit the coasts, where 

 they creep along upon a well-developed foot* others live in 

 the deep waters, where they cling to the stems of floating 



sea-weed with a nar- 

 row and furrowed 

 foot, or swim upon 

 their back, using the 

 borders of the man- 

 tle and of the bran- 

 chiae as oars. Though chiefly living in the warmer lati- 

 tudes, they are found in every sea, and many interesting 

 species inhabit the British waters : such as the Sea-lemon 

 (Doris tuberculata), which, when its horns and starry wreath 

 of branchiae are concealed, bears a curious resemblance in 

 size, form, colour, and warty surface to the half of a citron 

 divided longitudinally; the exquisite Eolis coronata, whose 

 crowded clusters of branchial papillae are radiant with crimson 

 and cerulean tints; and the crested Antiopa, whose transparent 

 breathing organs are tipped with silvery white. 



Though they' have no shell to cover them, the Nudi- 

 branchiata are not left defenceless to the mercy of their 

 enemies. The transparency of their body is a cause of 

 safety to many of them. Some conceal themselves under 

 stones or among the branches of the madrepores, and some 

 on contracting cast off a part of their mantle, which they 

 leave in possession of their hungry foe, while they themselves , 

 make their escape. 



Among the British Inferobranchiata we find the rare golden 

 or orange-coloured Pleurobranchus plumula, thus named from 

 its branchiae projecting like a plume from between the mantle 

 and foot in crawling; and among the Tectibranchiata the 

 common sea-hare (Aplysia punctata), which resembles a great 

 naked snail ; its back opening with two wide lobes, which can be 

 expanded or closed over the opening at the animal's will. When 

 open, they expose to view on the right side the finely fringed 

 and lobed branchiae, seated in a deep hollow beneath a fold oi 

 the mantle. The uncomely creature glides along over the stones 

 upon its flat fleshy foot and up the slender stems of sea-weeds 

 by bringing the borders of the same locomotive apparatus to 



