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ANIMAL LIFE-HISTORIES 



It will have been gathered from what has already been said, 

 that development is direct in some of the Higher Crustaceans, 

 but the stalk-eyed forms usually hatch out as larvae. This early 

 free-swimming stage in the life-history is, however, but very rarely 



Fig. 889. Life-history of Edible Crab (Cancer pagurus], enlarged. A, Young Zoaea. B, Fully formed Zosea. 

 c, Megalopa. D, Young Crab (during life the tail is bent up under body). 



a Nauplius, the most characteristic variety of larva being the 

 Zoaea, which is partially segmented, and otherwise of more com- 

 plex nature. In the life -history of the Edible Crab (Cancer 

 pagurus, fig. 889), for instance, the just-hatched Zoaea is a rather 

 ungainly-looking little creature, with large rounded cephalothorax 

 (i.e. head and thorax fused together) and slender limbless tail (A). 

 The large appendages shown in the drawing are foot-jaws, which 



