VII 



DEVELOPMENT 



385 



FIG. 99. Early embryo of the Crayfish in the nauplius stage. 



A in the upper part of the figure is the eye ; /. the labrum overhanging the mouth, 

 on either side of which are the rudiments of the antennules (a 1 .), antennae ( 2 .), 

 and mandibles (in.) ', behind them is the rudiment of the thorax and abdomen 

 (TA) with the anus (A). The rudiments of the first three pairs of ganglia 

 (G, ga~, gm^) are seen through the transparent ectoderm. (From Lang's Comp. 

 Anatomy, after Reichenbach.) 



FIG. TOO. Nauplius larva of Water-flea (Cyclops). (From Gegenbaur's 



Comp. Anatomy.) 



a, If, c, the three pairs of swimming appendages, representing the antennules, 

 antennae, and mandibles of the Crayfish : the median eye is seen between the 

 bases of the first pair. 

 PRACT. ZOOL. C C 



