866 THE OCEAN WORLD. 



this its infant state, when it has just left the protection of the parent 

 shell, the microscope reveals the young bivalve, with its shell perfect, 

 having an apparatus which is also a swimming pad, ready to 

 adhere to the first solid body which the current drives it against. 



This pad or cushion 

 (which is repre- 

 sented in Fig. 170) 

 is furnished with 

 vibratile cilia, dis- 

 posed round the 

 young shell. Aided 



by the powerful ad- 

 Fig. 1 70. Young Oysters furnished with locomotive organs. -\ i i -j-i 



which it is also provided, this cushion is projected through the water 

 at the will of the young inhabitant, which has every facility for the 

 purpose : it is even said to swim about near the mother, before final 

 dismissal from the maternal protection, seeking shelter at the least 

 alarm between the valves of the parent shell. The pad disappears 

 after the young oyster has finally attached itself to a permanent bed 

 of its own. 



Before this period of its life arrives, however, many are the dangers 

 to which it is exposed : its enemies are numerous ; they lie in ambush 

 for it in every cranny ! It has to guard itself against eddies and 

 currents, which would drive it out to sea, and mud banks, in which it 

 would be smothered. Crustaceans, worms, and polyps, with other 

 equally voracious marine inhabitants, prey upon it. Last, but not least, 

 come the terrible and multiplied engines of the eager fisherman 

 and we readily comprehend why the oyster is provided with such 

 accumulated masses of ova. 



If the young bivalve is fortunate enough to escape all the snares 

 and dangers we have enumerated, it grows rapidly. It is quite micro- 

 scopic at the period of its discharge from the parent shell ; at one month 

 it is of the size of a large pea, at the end of six months it is about 

 three-quarters of an inch, a year after its birth an inch and a half to 

 two inches, and finally, at the end of three years it has become mer- 

 chandise ; that is to say, it is in a state to be sent to the parks for 

 preservation and feeding. In Fig. 171 we see a group of oysters,* of 



* We give this illustration as representing the comparative size of the oysters at 



