232 EVENINGS AT THE MICROSCOPE 



shield composed of several pieces, stony in texture, on 

 account of the great development of their calcareous ele- 

 ment, and so modified in form as to make a low cone, the 

 legs (become the cirri, or what I have above called the 

 " fingers 7 ') made to perform their movements backward 

 instead of forward, and the whole abdomen reduced to 

 an almost invisible point. 



Marvellous indeed are these facts. If such changes as 

 these, or anything approaching to them, took place in the 

 history of some familiar domestic animal if the horse, for 

 instance, was invariably born under the form of a fish, 

 passed through several modifications of this form, imitat- 

 ing the shape of the perch, then the pike, then the eel, 

 by successive castings of its skin; then by another shift 

 appeared as a bird, and then, gluing itself by its fore- 

 head to some stone, with its feet in the air, threw off its 

 covering once more; and became a foal, which then grad- 

 ually grew into a horse or if some veracious traveller, 

 some Livingstone or Barth, were to tell us that such proc- 

 esses were the invariable conditions under which some 

 beast of burden largely used in the centre of Africa 

 passed should we not think them very wonderful? Yet 

 they would not be a whit more wonderful in this sup- 

 posed case than in the case of the Barnacle, in whose his- 

 tory they are constantly exhibited in millions of individ- 

 uals, and have been for ages even in creatures so common 

 that we cannot take a walk beneath our sea-cliffs, without 

 treading on them by hundreds! 



