faint; front wide. Rostral horns short, obtuse, 

 separated by a U-shaped notch. Preorbital angle 

 blunt, slightly produced. Basal article of antenna 

 with two teeth, inner one nearly as advanced as 

 rostrum, outer smaller one on orbital border. Or- 

 bit with four tubercles on margin, two superior 

 much smaller than external or inferior ones. An- 

 terolateral margin with four spiniform teeth, first 

 one obtuse, often bifid at tip ; second longer, sharp, 

 double, and curving forward; third and fourth 

 slender. Posterolateral border with a smaller 

 tooth situated higher on carapace in line with two 

 obliquely located tubercles, or a low spine and a 

 tubercle. Subhepatic region with two tubercles; a 

 few other tubercles on subbranchial and ptery- 

 gostomian regions. 



Chelipeds large, unequal in males, equal in fe- 

 males; merus with four or five spines and a few 

 tubercles on upper surface and two spines on inner 

 margin; carpus smooth; hand smooth; fingers 

 spooned at tips, gaping, with a broad low crenu- 

 lated tooth near base of dactyl. 



Measurements. — Carapace: large male, length, 

 102 mm. ; width, 146 mm. 



Variations. — Young individuals have tubercles 

 on the carapace more protuberant than in the old. 

 Color. — Nearly uniform deep brownish-red or 

 terra cotta color above, brighter on chelipeds and 

 darker on legs (due to brown hairs) ; legs often 

 with brighter red bands at joints; underparts of 

 body mostly white or bluish white; legs red, 

 speckled with pale yellow (Verrill, 1908). 



Habitat. — Commonly lives on rough bottom; 

 shallow water to 30 fathoms. 

 Type locality. — Unknown. 



Known range. — Recorded in literature from as 

 far north as Delaware Bay (Say, 1818), off 

 Charleston Harbor, S.C., and Georgia (Gibbes, 

 1850). Bahamas and Florida Keys through West 

 Indies to Sao Paulo, Brazil ; Bermuda. 



Mithrax (Mithrax) pleuracanthus Stimpson 



Figures 237, 245D 



Mithrax pleuracanthus Stimpson, 1871a, p. 116. — Milne Ed- 

 wards, 1875. p. 95. pi. 20. figs. 3-3f.— Rathbun, 1901, p. 68.— 

 Hay and Shore, 1918, p. 458, pi. 38, fig. 3.— Rathbun, 1925, p. 411, 

 pi. 150 (rev.). 



Mithrax depressus Milne Edwards, 1875 (in part), p. 96, pi. 20. 

 figs. 4-4c— Rathbun, 1901, p. 68. — Verrill, 1908, p. 407, pi. 23, 

 fig. 1. — Hay and Shore, 1918, p. 458, pi. 38, fig. 2. 



Mithrax hispidus Rathbun, 1892 (in part), p. 265. 



Recognition characters. — Carapace not much 

 wider than long, conspicuously tuberculate ; front 



Figure 237.— Mithrax (Mithrax) pleuracanthus Stimp- 

 son. Animal in dorsal view, legs of left side not shown, 

 10 mm. indicated. 



wide. Rostral horns shorter and wider than in 

 M. hispidus, notch between horns narrower and 

 nearly triangular, always triangular in young in- 

 dividuals. Preorbital angle blunt, slightly pro- 

 duced ; orbit with two superior tubercles ; a small 

 postorbital angle and a suborbital tubercle. Basal 

 article of antenna with two teeth, inner one nearly 

 as advanced as rostrum, outer smaller one on 

 orbital border. Spines of anterolateral border 

 well developed, anterior one or two inclined to be 

 double, posterior two more acute and pointed for- 

 ward, small tubercles about base of spines. Gas- 

 tric region with transverse row of five tubercles, 

 in front of these, two pairs of tubercles, anterior 

 pair at base of rostral horns. Mesogastric region 

 with two tubercles on each side in a transverse 

 line. Cardiac region with three poorly defined 

 tubercles. Branchial area with four rather strong 

 tubercles and several smaller ones arranged more 

 or less in three oblique rows radiating from car- 

 diac region to anterolateral border. 



Chelipeds large; merus with scattered low 

 spines on upper margin, with a simple spine, spine 

 and tubercle, or rounded eminence on inner mar- 

 gin, and five small spines on posterior border; 

 carpus smooth or with a few low tubercles on 

 upper surface; hands smooth; fingers slightly 

 gaping, dentate for nearly entire length, spoon- 

 shaped at tips. Walking legs dentate and hairy. 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



257 



