Zoology. 285 



illipeds. The former are De Haan's Grapsi, and RandalPs Pachy- 

 grapsi; the latter De Haan's Goniopses and Randall's GrapsL But 

 the length of this joint, as we have shown in many other cases, is a 

 characierisiic of small importance, and such a basis for subdivision is 

 therefore wrong. There are two natural groups; one with arcuate 

 sides, like G. p ictus, and the other with straight sides like G. cruenia- 

 tus and^ G. messor ; and in each, this joint may be short or oblong. 

 G, variegafus^ like G. piclus, has the joint oblong; yet a species 

 every way similar and hitherto referred to the variegatus has the same 

 jomt not longer than broad.* We hence reject ihis subdivision and 

 adopt two others, viz : Grapsus^ having arcuate sides, and Goniograp- 

 srts, having straight sides. The latter forms the transition to Sesarma 

 and G. cruentatus is like the Sesarma in habit. 



The genus Cyclograpsus of Edwards is characterized by its author 

 as havmg a piliferous crest on the outer maxillipeds, though exceptions 

 are admitted. Subsequently, M'Leay made his genus GnalhocTiasmus 

 on the same type. Some recent authors have taken M'Leay's nnme 

 for these typical species and restricted Cydogropsus to the exceptions. 

 *^e find no authority in the rules laid down by the British Association, 

 or in the nature of the case, for thus perverting Cyciograpsus from its 

 true type as first eslablished, and we therefore make Gnathochasmus 

 a synonym of it, and adopt a new name for the species without the 

 piliferous crest. This we believe is due to M. Edwards. 



The following is a synopsis of the Families, Subfamilies and Genera 

 of Grapsoidea : 



CRUSTACEA GRAPSOIDEA. 



I- ArtICULUS MAXILLIPEDIS EXTERNI 4tUS ANGULO StII INTEBNO 



articulatus. 



Fam. L GONOPLACID/E. 



Carapax transversus. Frons quarla parte latitudinis carapacis longior, 

 paulo deflexus, lamellalus. Antennae internsB transversce. Arliculus 

 abdominis maris 2dus sterno contiguo angustion 



G. 1. EucRATE, De HaanA — Carnpax anfice arcuatus, parce de- 

 clivis, Panopceo forma anrennisque affinis. Appendices maris^ 

 sexuales e sterno oriae abdomineque tectse. Pedes maris aniici 

 breves, crassi. Oculi breves. Abdomen maris 5-arliculatum, 

 versus basin sterno conliguo vix angustius. 



G. 2. CuRTOiNfOTUS, De /f«a/i.|— Carapax antice arcuatus, parce 

 declivis, margine antero^laterali rotundato. Appendices maris 

 sexuales e basi pedum ortse, in canaliculo sterni diiciae, deinde 

 abdomine teciK. Oculi breves. Pedes maris aniici prsRlongi. 



The 



. - species referred to is oup from Valparaiso. Tiie G. variegatus, according 

 to Its description bj Edwards, and the figure bj Guerin, has the joint quite oblong. * 

 ■I he Valparaiso ppecies, which we name the G^rapmn plauifrons, has thia joint no 

 ^oti^er than broud. 



t Crust Faun. Japon., p. 36. Geryon, Kroyer, Tidskrift, i, (1837,) p. 15, pi 1. 



; De Haan, Crust. Faun. Japon., p. 20. Pseiidorhambila, EdwurAd, Crust, ii, 68. 



