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Zoology. 195 
2. Regio carapacis postica transversim non conveza. 
€. Caxapax versus margines frontalem antero-lateralemque curvatim declivis. 
G. 5. Acrza, De Haan,* Dana.—Margo postero-lateralis brevis, 
sepius concavus.  Orbita hiatu externo non interrupta. 
6. Carapax versus margines frontalem antero-lateralemque parce declivis. 
a Orbita hiatu externo non interrupta. 
G. 6. XaxTno, Leach.—Margo antero-lateralis postero-laterali lon- 
gior. Articulus antennz externe lmus oblongus, frontem bene 
attingens, articulo sequente e apicis medio articuli 1mi orto. 
G. 7. EvxawrHus, Dana.—Xantho formá similis: articulus an- 
tennz externe lmus hiatum ad summum implens, articulo se- 
quente e latere excavato apicis orto. 
G. 8. PaARAxaxTHUS, Lucas.t— Xantho formá similis: articulus 
antennz externz lmus abbreviatus processum frontis oblongum 
attingens tantum. . Abdomen maris 5-articulatum. 
G. 9. MzuiPeE, De Haan.i—Margo antero-lateralis postero-lat- 
erali brevior. Articulus antennz externe brevis nec frontem 
- nec frontis processum attingens. Abdomen maris 7-articulatum. 
P Orbita hiatu externo interrupta, infra integra. 
G. 10. PaxoPzus, Edwards.—Margo antero-lateralis tenuis, pos- 
tero-laterali sepius brevior, ad orbitee angulum externum directus. 
y Orbita infra extusque tribus dentibus instructa, uno externo, duobus inferioribus. 
G. 1l. MEpzus, Dana.—MAngustus, paulo transversus, [nudus,] 
fronte sat brevi. Margo antero-lateralis sub orbitá productus. 
Abdomen maris 5-àrticulatam, segmento ultimo brevi. Pedes 
antici crassi, lis Xanthi similes. 
G. 12. HariuEDE, De Haan.S—Angustus, parce transversus, [vil- 
losus,] fronte breviore. Abdomen maris 7-articulatum, seg- 
mento ultimo valde elongato. Pedes antici crassi, iis Xanti 
similes.—An Pilumnis propinquior ? 
3. CHLORODINJE.—Antennz interne transverse. Antennzg externe 
- basi firmé infixe, parte mobili hiatu orbite raro exclusá. Frons 
interorbitalis latior. Digiti instar cochlearis excavati. —Quoad genera, 
Xanthinze et Chlorodinz ferme parallela. 
* Faun. Japon. 18. 
1 Crust. D'Orb. S. Am.,, 18. We see no sufficient character for sustaining this 
genus, excepting the short basal joint of the outer antennz. 
j Faun. Jap. 21 .—JPseudocarcinus of Edwards, Crust. i, 407 .— Peleus, Eydoux and 
Souleyet, Voy. de. la Bonite. Peleus armatus is the name given to a "Sandwich 
Island species figured in the plates of the Bonite, but not yet described. 
8 Faun. Japon. 35. Our Medeus has nearly the outline of Halimede, but is na- 
very deeply areolate. It isa Xantho in nearly all its characters , though 
narrow, and havin the orbit below deeply divided. On this account, I have intro- 
duced "Halimede, "which resembles our genus in form, in this place, not having had 
an opportunity to study its characters from specimens. 
