138 THE SEA-SIDE AND AQUAKIUM. 



the roof of a house, or like the mail plates on some 

 knightly gauntlet. 



It generally measures from half to three quarters 

 of an inch in length, although on foreign shores it 

 attains a much greater size. A specimen now before 

 me is exactly two inches long. The colour of this 

 animal is dark brown. Its mode of locomotion, and 

 general character, are precisely the same as those of 

 the Limpet. 



Such animals as the Chiton, Limpet, and others 

 resembling them, belong to a species of molluscs 

 called Gasteropoda, which are so named from their 

 locomotive organs being attached to the under part of 

 their bodies. They are, however, to a certain extent, 

 armed against attack or danger by a shelly covering. 



There is another class of molluscs that creep about 

 without any such protection, and whose gills or lungs, 

 instead of being inside, are exposed on the exterior 

 of their bodies. These are hence called Nudibranchs, 

 or Naked-gilled Molluscs. The Doris and Eolis are 



THE EOLIS. 



types of this class. The gills of the former are spread 

 out in an arborescent form, and have a most elegant 



