2O0 The St?cdy of Animal Life part m 



starting of course as an ovum at the level of the Protozoa, 

 has to stop as it were at the first distinctively crustacean 

 station — the Nauplius stage. After some change and 

 delay, it continues to progress, but again there is a halt and 

 a change at the Zoea station. Finally there is another 



- Life-history of Pcntrus ; tlie Zoca. 



delay at the Mysis stage before the Pcjiccks reaches its 

 destination. The crab, on the other hand, stops first at 

 the Zoea station, the lobster at the jMysis station, while the 

 crayfish though progressing very gradually like all the 

 others has — if you do not find the simile too grolescjue — a 

 through-carriage all the way. 



