THE CANCROID CRABS OF AMERICA 333 



Genus PANOPEUS Milne Edwards 

 MUD CRABS 



Panopeus Milne Edwards, Hist. Nat. Crust., vol. 1, 1834, p. 403; type, P. herbslii 



Milne Edwards. 

 Eurypanopeus Rathbun, Proc. Biol. Soc. Washington, vol. 11, 1897, p. 165 (part; 



not Eurypanopeus A. Milne Edwards 1880). 

 Eupanopeus Rathbun, Bull. Lab. Nat. Hist. State Univ. Iowa, vol. 4, 1898, p. 



273. Substituted for Panopeus which was rendered invalid by Panopea Menard 



1807, according to a rule since reversed. 



Carapace of moderate width, length two-thirds to three-fourths 

 the width, moderately convex, the regions fairly well delimited, 

 crossed by broken, raised, transverse lines on anterior half. Antero- 

 lateral borders horizontal or slightly upturned, shorter than postero- 

 lateral, arcuate, tending to subquadrate, cut into five teeth, including 

 orbital angle, wiiich is more or less fused with the next tooth; the 

 third, fourth, and fifth are usually well-marked and distinctly denti- 

 form; outer margin of all the teeth sublaminar; postero-lateral bor- 

 ders moderately convergent, straight. Fronto-orbital border more 

 than half the greatest wddth of carapace. Front between a third and a 

 fourth the greatest width of carapace, horizontal or slightly deflexed, 

 laminar, with a median notch, and two sinuous lobes, separated from 

 the more elevated inner angle of orbit by a notch. Orbital margin 

 with two small but distinct U-shaped notches above, continued 

 backward by closed fissures, and a broad notch below outer angle. 

 A prominent tooth at lower inner angle. Orbits transversely oblong, 

 not tightly filled by the eyes. Inner portion of anterior margin 

 of basal article touches the front; its outer angle is prolonged into 

 the broad orbital hiatus, but does not exclude flagellum from orbit. 



Merus of outer maxillipeds transverse, its anterior margin more or 

 less sinuous. Chelipeds unequal in both sexes; the merus has a 

 superior subterminal tooth ; the carpus a tooth at inner angle ; fingers 

 acute, movable fingei of large cheliped with a large basal tooth. 

 Legs rather thick, compressed; hornj^ tip of dactylus of last pair 

 recurved backward (not upward), that is, the tip does not lie in the 

 same plane as the remainder of the limb. Abdomen of male 5-seg- 

 mented. 



From Massachusetts to State of Santa Catharina, Brazil; Baha- 

 mas: Bermudas; west coast of Mexico to Chile. West Africa. 



KEY TO THE AMERICAN SPECTES OF THE GENUS PANOPEUS 



A^ Five lateral teeth, the first two always distinguishable but generally more or 



less fused. 



B'. Dark color of immovable finger continued more or less on palm, especially 



in males. 



C. Carapace narrow, length to width approximately as 1:1.35 or 1.36. 



D'. Carapace depressed, fourth lateral tooth wider than third, 



measured from sinus to sinus americanus, p. 357. 



D2. Carapace high in middle, fourth lateral tooth narrower than 

 third herbstii forma simpsoni, p, 337 



