202 THE CRAYFISH. PHYLUM ARTHROPODA 



six legs while two— which are on opposite sides and of different 

 pairs — are in motion. 



Fig. 135. — View of a crayfish from the right side. 



ab.l/j, Sixth abdominal limb ; o/.i, antennule ; at. 2, antenna ; br., branchiostegite ; e.g., cervical groove; 

 ck., cbeliped ; crd., cardiac region of carapace ; en., endopodite ; ex., exopodite ; mxp.-i, third maxilliped; 

 yi., pieuron ; pr., protopodite ; rsL, rostrum ; sea., scale of antenna ; /., telson ; tg., terga ; w.l.^, last 

 walking leg. 



