116 THE AQUARIAN NATURALIST. 



rolled away since these little zoophytes began to live, 

 and toil, and die, and leave behind inscribed in every 

 stone the record of their industry ; and yet two cen- 

 turies have not elapsed since man for the first time 

 suspected their existence since man first became 

 aware that such things are, much less that such 

 things had been, and had perished. Surely the sage 

 was not far wrong who said, that science was a little 

 boy employed in picking up pebbles upon the shore, 

 as specimens of the vast wealth concealed beneath the 

 limitless expanse of ocean. 



The Hydr actinia squamata (PL II. fig. 3) is one of 

 those remarkable productions of Nature so singular in 

 its appearance, and so dissimilar in its structure from 

 the generality of the Polyp race, that the young 

 naturalist is at first quite at a loss what to think of it ; 

 and were it not for its slow and languid movements 

 when examined under the microscope, it would be 

 difficult to imagine a creature so strangely formed to 

 be a member of the race of Hydroid Zoophytes, to 

 which, on a closer study, it is found indubitably to 

 belong. It is a Tubularia, in fact, but widely dif- 

 ferent in shape from the zoophytes whose history we 

 have hitherto had an opportunity of discussing. 



The Hydractinia is one of those animals after which 

 it is vain to institute a special search ; nevertheless, 

 an auxiliary frequently comes to our assistance when 

 least expected, a creature most opposite in form, 

 nature and habits the Hermit Crab. 



From the necessity of protecting part of its body, 

 as we shall see afterwards more at length, the Hermit 

 Crab is obliged to take possession of an empty shell, 



