* 



284 Scientijic Intelligence, 



Ihe former characterized by the absence of this crest. A survey of 

 the groups will al once show, we believe, that we follow natural lines 

 in this subdivision. The PlagusincB are distinguished by longitudinal 

 sinuses in the front of the carapax for the inner antennse. 



The family Gecarcinid^ — the fourth — is the same in limits as the 

 ^'Gecarciniens" of Edwards, — ^ihe species are remarkable for their 

 thick obese forms, high rounded front and antero-lateral margin, and 

 for having the second joint of the male abdomen but slightly narrower 

 than the corresponding part of the sternum. 



The family P1NN0THERID.E — the fifih— differs from the " Pinnothe- 

 riens" of Edwards in the removal of the genus Do/o, closely related 

 to Ocypod, and also the genus Myctiris^ an aberrant form between 

 Pinnoihera, Doto and Heloecius, but very peculiar in being narrow an- 

 teriorly, and having no distinct orbits for the retraction of the eyes. 

 The genus Myctiris constitutes the last or sixth family MyctiriDjE. In 

 the Pinnotheridae, the male abdomen is much narrower than the ster- 

 num behind, which character separates them from the Gecarcinidse, 



We do not believe in a properly lineal order in classification ; yet 

 the succession we have given to the families is a natural succession, as 

 nearly as can be made. Theirs/, Gonoplacidae, link the Grapsoidea 

 with the Cancroidea, and the genus Eucrate is very near Eriphia and 

 Panopaeus in form. The second^ Macrophthalmidce, is closely allied 

 to the first, so much so that Marophthalmus and Gonoplax have been 

 arranged in the same group. The //nVrf, Grapsidre, are again very 

 near the Macrophlhalmidte, and the genus Helice is almost as correctly 

 placed with one as the other. Thence the transition is as gradual also 

 to ihe/o«r//i or Gecarcinidae, and from the fourth to iUeffih or Pinno- 

 iheridce, and from the fifth to the sixth or Myciiridse, Still, there are 

 other relations of somewhat less prominence which this order does not 

 exhibit. That of Elamena to Inachus has long been recognized. 



The Gonoplacidce are placed in the Cancer group by DeHaan, who 

 neglected the important distinction based on the male verges. The 

 other genera, exclusive of Pinnothera and the species related, he divides 

 into two groups, the Ocypus and Gropsns groups, the former havlnij the 

 fourth joint of the outer maxillipeds articulated wiih the outer angle of 

 the third, and the latter, articulated with the middle of the apical mar- 

 gin ; — a distinction difficult to carry out and dividing natural groups, as 

 the Gecarcinidfe, Grapsidse, &g. His genera of the Ocypus group, 

 are, Doto, Scupimera, Myelins, Gelasimus, Macrophthalmus, Cleistos- 

 toma, Cardisoma, Chasmagnathus, Helice, Uca, Ocypoda, Acanthopus 

 (a division of Plagusia) ; those of the Grafsus group, are, Gecarcinus, 

 Philyra (division of Plagusia), Plagusia (another division), Grapsus, 

 Trichopus, Eriocheir, Pachysoma, Goniopsis, Platynotus, Brachynotus, 

 Nautilograpsus, Cyclograpsus, and in his " Decas Septima," published 

 in 1849, he unites with the group, Pinnotheres and Hymenosoma. 



We add a few words on the genera of GaAPSiDiE. Both De Haan* 

 and Raiidallt have divided the Grapsus of authors into two genera, ac- 

 cording to the short or oblong form of the third joint of the outer max- 



f 



* Faun. Japon., p. 33, 18.S3. 



t Jour. Acad. Nat. ScL, Phiiad., viii, 124, 126. 



