358 



VERTEBRATA : CRUSTACEA. 



FIG. 482. 

 st ms oa 



\ 



\ \ 



fa lr K aa af br' 



Crab, with most of the shell of the Cephalo-thorax removed. 



TO, membranous lining of the shell; h, heart; ta, ophthalmic artery; aa, abdominal 

 artery; br, branchue or gills; br', branchiae turned back; af, arch of the flancs; fa, 

 flabelliform appendix of the limb-jaws; st, stomach; ms, muscles of the stomach; I, 

 liver. 



Metamorphosis of the Crab. 

 A, first or zoea stage; B, second stage: C, third stage; D, perfect form. 



