112 NATURAL HISTORY OF OUR SHORES 



name, Anatifera ("goose producing" or "bearing"), is a 

 survival of the old belief. 



I could give some humorous quotations from the 

 ancient naturalists (Gerald, Sir John Maundeville, and 

 others), but they would serve no useful purpose, and we 

 must, at least, try to think charitably of these old writers, 

 and remember that while " Errors which we spurn to day 

 were the truths of long ago " it is possible that some of 

 our " truths " will prove to be error presently, although 

 I am optimistic enough to believe that, in natural science, 

 at least, we now stand upon a pretty firm rock. 



The embryology of the ship -barnacle has now been 

 watched and studied, even by the least among the disciples 

 of natural history, and its place in nature is well decided. 



To understand it fairly we must trace its life history. 



From an egg cast from (or hatched within) the parent, 

 issues a little free-swimming organism termed a Nauplius, 

 or, better, the " Nauplius stage " of the barnacle. 



This is a minute, shield-shaped thing, about the size of 

 a small pin's head. It feeds voraciously, changes its coat 

 repeatedly, and makes some structural changes at each 

 moult e.g. it develops more legs, and then a pair of eyes, 

 alongside of an original one. It travels rapidly through 

 the water, back downward, with little jerky movements. 



(This " Nauplius stage " is not confined to the Cirripedes, 

 some other crustaceans develop in a similar way, among 

 them a large prawn, Peneas.) 



After a few moults it makes an important change. It 

 quits the Nauplius form, and develops two little concave 

 valves, like mussel shells, one on each side of its body, and 

 between which it can withdraw its legs. 



It now closely resembles a crustacean of the next division, 

 the Entomostraca. 



In fact, it is very like the Cypris of our ditches, and is 

 said to be in the " Cypris stage." 



