16 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



B\ Carapace xanthoid, widest behind the postorbital angles. Orbits of nor- 

 mal size and form Subfamily Carcinoplacinae, p. 17. 



Cf. Eyes movable. • 



D\ Carapace subquadrate ; posterolateral margins nearly parallel. Rlax- 



llleds gaping Trizocarcinus, p. 17. 



Dl Carapace hexagonal ; postero-lateral margins distinctly converging 



posteriorly. Maxillipeds not gaping Pihimnoplax, p. 21. 



C*. Eyes immovable Dathtjplax, p, 19. 



B*. Carapace subquadrate, anterior border entirely occupied by square-cut 

 front and orbits, the latter being long, narrow trenches. Carapace 



widest between the postorbital angles Subfamily Goneplacinac, p. 24. 



Goncplase, p. 25. 

 A*. The base of the third segment of the male abdomen does not cover the 

 whole space between the last pair of legs. 

 B\ Width of male abdomen at third segment more than half width of ster- 

 num in same line Subfamily Prionoplacinae, p. 29. 



C\ Fronto-orbital width almost as great as the total width of the cara- 

 pace. Eyestalks long. Carapace of ocypodine form, subquadrate; 

 postero-lateral margins converging. 



D'. Antennae excluded from the orbit Euryplax, p. 34. 



D". Antennae entering the orbit. 



E'. Carapace wide. IMerus of outer maxilliped broader than long. 



F\ Carapace quadrilateral Prionoplax, p, 29. 



F^ Carapace hexagonal Chasmophora, p. 37. 



E*. Carapace narrow. Merus of outer maxilliped as long as broad. 



Tetraplax, p. 32. 

 C*. Fronto-orbital width from one-half to three-fourths the total width of 

 'the carapace. Eyestalks short. Antero-lateral margin arcuate. 

 D\ Eyestalks diminishing to the tip. 



E*. Postero-lateral margins converging postei'iorly Cyrtoplax, p. 45. 



E*. Postero-lateral margins subparallel Speocarcinus, p. 38. 



D*. Eyestalks enlarged at the corneal end. Postero-lateral margins 

 distinctly converging posteriorly. 

 E\ Fronto-orbital border about half total width of carapace. 

 F\ Upper surface of carpus of cheliped subrectangular. 



Pseudorhomhila, p. 42. 



F*. Upper surface of carpus not subrectangular Oediplax, p. 44. 



E*. Fronto-orbital border from three-fifths to three-fourths of the total 

 width of the carapace. 



F'. Carapace broad, width 1^ times length I'<inoi)/ii.v. p. 47. ■ 



F'. Carapace narrow, width about IJ times length. 

 G\ Merus of outer maxillipeds with antero-external angle promi- 

 nent, acutangular Glyptoplax, p. 48. 



G'. Merus of outer maxillipeds with antero-external angle not 



prominent nor acutangular ^Eiicratopsis, p. 52. 



B\ Width of male abdomen at third segment less than half width of sternum 



in same line Subfamily RMzopinac, p. 54, 



Chasmoearcinus, p. 54. * 



^Ceratoplax ciliata Stimpson (Proc. Acad. Nat. Sci. Philadelphia, vol. 10, 1858, p. 96 

 [42].— Mlers, Challenger Kept., Zool., vol. 17, 1886, p. 234, pi. 19, flgs. 3-36), an Indo- 

 Paciflc species. Is recorded by Cano (Boll. Soc. Nat. Napoli, ser. 1, vol. 3, 1889, p. 229) 

 from the coast of Ecuador. He regards his identification as doubtful (p. 91) and on 

 p. 101 says simply " Ceratoplax sp." No description is given. If the locality cited be 

 correct for the specimen, it is more liltely to have been a species of Chasmoearcinus. 



