16 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



B 1 . Carapace xanthoid, widest behind the postorbital angles. Orbits of nor- 

 mal size and form Subfamily Carcinoplacinae, p. 17. 



C 1 . Eyes movable. 

 D 1 . Carapace subquadrate ; postero-lateral margins nearly parallel. Max- 



llleds gaping Trisocarcinus, p. 17. 



D'. Carapace hexagonal ; postero-lateral margins distinctly converging 



posteriorly. Maxillipeds not gaping Pilumnoplax, p. 21. 



C*. Eyes immovable Bathyplax, p. 19. 



B 1 . 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 Goncplacinae, p. 24. 



Goncplax, p. 25. 

 A 1 . The base of the third segment of the male abdomen does not cover the 



whole space between the last pair of legs. 



B 1 . Width of male abdomen at third segment more than half width of ster- 

 num in same line Subfamily Prionoplacinae, p. 29. 



C 1 . 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 1 . Antennae excluded from the orbit Euryplax, p. 34. 



D". Antennae entering the orbit. 



E 1 . Carapace wide. Merus of outer maxllliped broader than long. 



F 1 . Carapace quadrilateral Prionoplax, p. 29. 



F". Carapace hexagonal Chasmophora, p. 37. 



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



Tctraplax, p. 32. 

 C 1 . Fronto-orbital width from one-half to three-fourths the total width of 



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

 D 1 . Eyestalks diminishing to the tip. 



E 1 . Postero-lateral margins converging posteriorly Cyrtoplax; p. 45. 



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



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



distinctly converging posteriorly. 



E 1 . Fronto-orbital border about half total width of carapace. 

 F 1 . Upper surface of carpus of cheliped subrectangular. 



Pseudorhombila, p. 42. 



F 3 . Upper surface of carpus not subrectangular Oediplax, p. 44. 



E 1 . Fronto-orbital border from three-fifths to three-fourths of the total 

 width of the carapace. 



F 1 . Carapace broad, width 1$ times length I'tnioplu .1-, p. 47. 



F 1 . Carapace narrow, width about 1J times length. 

 G 1 . 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 Eucratopsis, p. 52. 



B 1 . Width of male abdomen at third segment less than half width of sternum 



in same line Subfamily Rliizopinac, p. 54. 



Chasrnocarcinus, p. 54. * 



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

 [42]. Miers, Challenger Kept., Zool., vol. 17, 1886, p. 234, pi. 19, figs. 3-3Z>), 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 likely to have been a species of Chaamocarcinus. 



