GRAPSOIDEA. 331 



of Randall, and hence to avoid confusion, we do not adopt either of 

 these generic names. The cruentatus is so like the messor and plicatus 

 in habit, that we cannot disjoin them on the grounds of the difference 

 alluded to; and it -is so different from the pictus in this respect (the 

 former a salt marsh species, the latter like the variegatus and plani- 

 frons a rapid runner over the rocks of an open sea-shore), that we 

 cannot believe in the propriety of their union. 



Other changes have been found necessary, besides the introduction 

 of some new genera. For example, it appears that Gnatliochasmus of 

 M'Leay, and Cyclograpsus of Edwards, were introduced upon related 

 types, and are essentially identical, and that the latter must be retained 

 as having the precedence in time. A portion of Edwards's Cyclo. 

 grapsi, not having the typical character and not answering to his 

 description (requiring the third joint of the outer maxillipeds to be 

 crossed by an oblique piliferous crest), forms naturally a distinct group. 

 They are true Grapsince, while the Cyclograpsi are Sesarmince. We 

 have not felt at liberty to adopt M'Leay's name for Cyclograpsus, and 

 Cyclograpsus for the latter group, as is done by Gray, in the Catalogue 

 of the Crustacea of the British Museum, as we are at no liberty to 

 misuse Edwards's name; and we therefore give the second group 

 a distinct name, calling it Hemigrapsus. As above stated, the species 

 are De Haan's Grapsi. 



Other changes introduced will be remarked upon beyond. 



A constant characteristic of the Grapsidae is the division of the 

 palate by a ridge separating the efferent channel from the middle of 

 the plate, as in the Eriphise, and most Portunidae. This peculiarity 

 separates them from the Gecarcinidse, and from most, also, of the 

 Macrophthalmidae. The Eriphida3, in the palate or efferent channel, 

 as well as general form, are thus the connecting link between the 

 Cancrinea and Grapsidse. 



The following is a synopsis of the subfamilies and genera of Grap- 

 sidge : 



1. GKAPSIN^JE. Antennae internee fronte tectae. Articulus maxil- 

 lipedis externi 3tius costa obliqua in 2dum producta non ornatus. 



1. Maxillipedes externi vix Jiiantes. 



Gr. 1. PsEUDOGRAPStis, Edw. Articulus maxillipedis externi Stius orbieulato- 

 cordatus, aut subquadratus, 2do brevior. Frons dimidio latitudinis carapacis vix 

 brevior. Carapax lateribus arcuatus, 



