274 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



E. Pleon with segments not overlapping. Rostrum minute or absent. Car- 

 apace short. First pair of legs chelate. Eyes small. Burrow- 

 ing shrimps Tribe Te-ialassinidea. 



Family CALLlANASSIDiE. 



E'. Pleon with segments overlapping. 



F. First pair of legs simple or only subchelate. Carapace with very thick 



integument Tribe Loricata. 



G. Carapace subcylindrieal; external antennae very long and rigid. 



"Spiny lobsters" Family f-alinurid^. 



. G'. Carapace flattened; external antennae flat, short, squamiform. 



Family scyllarid^. 

 F'. First pair of legs chelate. Carapace with moderately firm integument. 



Tribe Porcellanidea. 



Family PORCELLANIDyE. 



B'. Body more or less compressed. Rostrum usually compressed. Pleon elongate, 

 not inflexed; appendages oar-shaped, j^rticulation between 

 the carpus and propodus at only one fixed point. 



Tribe Caridea. 

 C. First three pairs of legs chelate; rostrum laterally compressed. 



Family pen^id^e. 

 C First three pairs of legs not all chelate. 



D. Rostrum long; first and second jjairs of legs chelate; last three pairs 

 simple. 

 E. Second pair of legs with carpal joint undivided. Sometimes fluviatile. 



Family pal.emonid^. 

 E'. Second pair of legs with carpal joint divided into segments. 



Family hippolytid^. 



D'. Rostrum very small or absent. 



E. Eyestalks short, more or less covered by the projection of the front 



margin of the carapace; first pair of legs robustly chelate, 



sometimes unsymmetrical ; second pair long and slender, 



minutely chelate Family alpheid^, 



E'. Eyestalks not covered bj^ the front margin of the carapace. 



F. First and second pairs of legs distinctly chelate, with spoon-shaped 



fingers. Fluviatile Family atyid.e. 



F'. First and second pairs of legs more or less chelate. Fingers not spoon- 

 shaped. Marine Family CRANGONiDiE. 



Suborder BRACHYURA. 



Tribe CATOMETOPA. 

 Family OOYPODID^. 



KEY TO THE WEST AFRICAN GENERA OV THE FAMILY OCYPODIL)^.. 



A. Carapace quadrate; sides entire; front narrow; orbits occupying nearly the 

 whole width of the carapace. 



B. Eye peduncles large ; chehe in male somewhat unequal Ocypode. 



B'. Eye peduncles slender; cbehe in male extremely unequal Uca, 



A'. Carapace with arcuate anterior margins; front and orbits of moderate width. 



B. Antero-lateral margins distinctly dentate Pilumnojilax. 



B'. Antero-lateral margins obscurely lobate Typhlocarcinus. 



