GRAPSOIDEA. 



331 



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

 these generic names. The cruentatus is so like the messar 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 Qnathochamnus of 

 M'Leay, and Gyclorjrapsus 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 Qrapsince, 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 Haarfs Grapsi. 



Other changes introduced will be remarked upon beyond. 



A constant characteristic of the Grapsidaa 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 Portunidge. This peculiarity 

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

 Macrophthalmidaa. The Eriphidae, in the palate or efferent channel, 

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

 Cancrinea and Grapsidae. , 



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

 sidae: 



1. GBAPSINiE. — Antennae internae fronte tectse. Articulus maxil- 

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



1. JMaxiUipedes externi vix Mantes. 



Gr. 1. Pseudograpstjs, Edw. — Articulus maxillipedis externi 3tius orbiculato- 

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

 brevior. Carapax lateribus arcuatus. 



