182 SHELLS AND MOLLUSCOUS ANIMALS. 



So rotten planks of broken ships do change 

 To barnacles. O transformation strange ! 

 'Twas first a green tree, then a broken hull, 

 Lately a mushroom, now a flying gull." 



Gerarde's picture is very amusing, as the young 

 geese are represented as having their heads out of 

 the shells, which are hanging on the branches, and 

 seem as if calling to their companions gliding be- 

 neath them. Our great naturalist, Ray, however, 

 whose work was published in 1678, opposed the 

 popular notion, and a writer has ridiculed it a cen- 

 tury earlier. 



But leaving the barnacle tribe, we turn to some 

 equally common molluscous animals which have no 

 shells, but have a cartilaginous, flexible tunic, or 

 outer coat. They are on this account called tuni- 

 cated mollusks. Often in our rambles along the 

 shore we pick up one of those strange looking 

 things, commonly called sea-squirts (Ascidice), 

 which have been thrown up from the sea by storms, 

 or which sometimes seem growing on the stones, 

 or large dark sea- weeds which lie among the rocks, 

 If we press them ever so gently, we are imme- 

 diately saluted by a jet of water. These animals 

 consist of a shapeless sort of bag, sometimes of a 

 pale brown colour, though often marked with 

 beautiful and bright tints, and they have so little 

 the appearance of animals, that we should at first 

 hardly recognise them as living things, were it not 

 for their habit of ejecting the liquid. This water 

 issues from two openings in the rough skin. They 

 feed on the contents of the water, which are brought 

 to the mouth by the current. As yet the habits 

 of these Ascidias are little understood ; but it has 

 been ascertained, that while in an earlier stage of 



