TUOEACOSTEACA. 



467 



lobed and used as jaws ; the four anterior maxillipeds are biramous 

 and act as biramous swimming feet ; and behind them, in the macru- 

 rous Decapods, the maxilliped of the third pair also appears as a 

 biramous swimming foot. Gills are as yet wanting, being repre- 



FIQ. 367. Larva of Penaeus (after Fr. Muller). a, Nanplius form seen from the dorsal sur- 

 face. 5, Metanauplius stage seen from the left side; 3Ix', anterior maxillae; Mx' 1 ', pos- 

 terior maxillee; 61, sixth and seventh pairs of appendages or first and second 

 maxillipeds* c, Zoaea stage ; 0, eyes. 



sented by the thin surfaces of the sides of the cephalo-thoracic 

 shield, beneath which a continual current of water flowing from 

 behind forwards is kept up. A short heart with one or two pairs 



