STALK-EYED CRUSTACEA 451 



I. Penaeus. 



Penmcs .... Spence Bate, Fabricius, Latreille, 

 Lamarck, Leach, Desmarest, 

 Roux, H. Milne Edwards. 



Palenwn .... Olivier. 



Body compressed, especially posteriorly. Carapace 

 with rostrum, which is more or less dorsally serrated. 

 The eyes are large and longitudinally ovate. The 

 internal antennas have the first joint deeply excavated 

 on the upper surface, and furnished on the inside with a 

 flat process that has a hairy margin, and on the outside 

 with a spine. Each terminates in two flagella that are 

 never longer than the carapace. The basal scale of the 

 external antennae terminates in a sharp tooth on its 

 outer margin ; the inner margin is thin, and is fringed 

 with long hairs. The first basal joint has a tubercle 

 on the inner side, and the third has a hook on the upper 

 surface. 



The first maxillipede is seven -jointed, short, and 

 subpediform ; the last three joints are reflexed, and 

 flattened on the inner margin. The external appendage 

 has two joints ; the first round, the second flat and 

 margined with hairs. The external maxillipedes are 

 seven-jointed, pediform, and long. 



The first three pairs of legs are chelate, increasing in 

 size from before backwards, and each of them has an 

 external appendage from the basal second joint. 



The last two pairs of legs are not longer than the 

 preceding ; they are slender, and terminate in a simple 

 finger. 



The abdominal appendages are large and two- 

 branched, except the first pair, which, in the male, has 



