STALK-EYED CRUSTACEA 3 



Flagella of antenn.ie very short. External maxillipedes 

 flat, closing the mouth like a door. Buccal cavity 

 distinctly defined in front. — i^Bracliyiira.) 



II. Abdomen sometimes bent under the body, some- 

 times extended, nearly always having some appendages. 

 Sternum very narrow between the last three pairs of legs. 

 Last pair of legs usually atrophied. — {Anomoura.) 



III. Abdomen large, extended backwards, with lamellar 

 appendages beneath. The appendages of the last segment 

 and of the last segment but one enlarged, forming a fan- 

 like swimming organ. Sternum narrow. Antennas well 

 developed. External maxillipedes pediform. Buccal 

 cavity not distinctly defined in front. — {Macronra.) 



Suborder I. Brachyura. 



BracJiyura .... Leach, Latreille, Dana, Linne, 



Claus, Haswell, Miers. 

 BracJiyures . . . H. Milne Edwards. 

 Cancri Brachyiiri . Lamarck. 

 Klistosinatha . . . Fabricius. 



Tetrogonostonia 

 Trigonostonia 



Macleay. 



The abdomen, folded under the body into a median 

 groove, is little developed, never has false swimming feet, 

 and is never used as a swimming organ. The sternal 

 plastron is of some size and never linear. The genital 

 orifices of the female are always situated on the sternal 

 plastron. The flagella of the antennae and antennules 

 are generally short or rudimentary. The external 

 maxillipedes, flat, are like doors hinged at the lower ex- 

 ternal corner, and may completely close the mouth, which 



