The eggs are normally laid during the spring and 

 summer in the year following the mating of the 

 parents. The eggs of a single batch number in the 

 neighborhood of one million. 



3. The young when first hatched are called zoea 

 larvae. During the zoea stage they increase in size 

 by molting. In this stage the probable number of 

 moltings is five. 



4. The second larval stage is known as the 

 megalops. From five to six weeks are required to 

 complete the two larval stages. The megalops is 

 not known to molt before passing directly into the 

 young crab form. 



5. In passing from the megalops to the adult- 

 crab stage, molting occurs twelve times. The final 

 molting of the female is accompanied by a change 

 in the form of her abdomen from a triangular out- 

 line to a form broad and round. The abdomen of 

 the male remains constant in form. Nor does it 

 appear that he molts after reaching maturity. 



6. The life of the spider-crab is three years. 



7. Resection of the cerebral mass shows that self- 

 concealment in Hyas coarctatus is reflexive, a fun- 

 damental part of instinct that can be separated 



[270] 



