o g CRUSTACEA. 



inner antennae are longitudinal, as in the Ocypods, to which they 

 have close relations; but the body is very narrow in front, and 

 rounded tumid instead of quadrilateral. 



The following is a brief recapitulation of the characters of these 

 several families. 



CRUSTACEA GRAPSOIDEA. 



1. ArticuJus maxiUipedis extern i 4.tus angido otii inferno artieu/atus. 



Fam. I. Gonoplacidje. — Carapax transvcrsus. Frons quarta parte 

 latitudinis carapacis longior, paulo deflexus, lamellatus. Antennae 

 interna? transversse. Articulus abdominis maris 2dus sterno con- 

 tiguo angustior. 



( c l 



2. Articulus maxiUipedis externi 4/w.s migulo otii apicali interna non articulatus sed 

 medio margmis opicalis sire angido externa. 



Fam. II. Macrophthalmidje. — Oculi tertia parte latitudinis carapacis 

 non breviores. Carapax subquaclratus sarpissime transvcrsus, an- 

 tice latissimus, angulis anticis acutis, lateribus non arcuatis. An- 

 tennae interna? sive transversa?, sive longitudinales. Articulus 

 abdominis maris 2dus sterno contiguo angustior. Articulus maxil- 

 lipedis externi otius crista obliqua pilifera nunquam ornatus. 



Fam. III. Grapsid^e. — Oculi tertia parte latitudinis carapacis brevi- 

 ores. Carapax subquadratus, sa^pius depressus, lateribus aut rectis 

 aut arcuatis. Antennse interna 1 transversa?. Articulus abdominis 

 maris 2dus sterno contiguo sa^pius vix angustior. Articulus max- 

 iUipedis externi otius sive inornatus sive crista obliqua pilifera 

 ornatus. Palatum colliculo vise efferentis liinite instructum. 



Fam. IV. Gecarcinid^:. — Oculi breves, Carapax obesus, paulo trans- 

 versa, antice latus, curvatim declivis, lateribus arcuatis poneque 

 oculos large rotundatis, vix dentatis. Antenna? interna 1 transversa?. 

 Articulus abdominis maris 2dus sterno postico vix angustior. Arti- 

 culus maxiUipedis externi otius crista obliqua pilifera non ornatus. 

 Palatum colliculo via? erferentis limite non instructum. 



