THE SPIDER CRABS OF AMERICA 



407 



Mus., vol. 15, 1892, p. 265 (part; pleuracanihus excluded). — Verrill, 



Trans. Conn. Acad. Arts and Sci., vol. 13, 1908, p. 404, text-fig. 40, pi. 

 23, figs. 3 and 4; pi. 24, fig. 1. 

 Mithrax Desbonxe and Schramm, Crust. Guadeloupe, 1867, p. 8, pi. 2, 



figs. 4 and 5. 

 Mithrax depressus A. Milne Edw.\rds (part). Crust. R<5g. Mex., 1875, p. 



96, not pi. 20, figs. 4-4c (specimens from Woman Key; 7 cotypes in 



M. C. Z.). 



Diagnosis. — -Three antero-lateral branchial spines, the anterior one 

 of which is bifid, and a postero-lateral spine. Rostral sinus dis- 

 tincth' U-shaped, as wide, or nearly as wide, as either horn. Two 

 spines on anterior margin of arm. 



Description. — Carapace swollen, considerably wider than long, 

 smooth, except for some low, rounded prominences chiefly toward 

 the outer margin of the branchial region. 

 Gastric tubercles very faint. Front 

 wide; horns short, obtuse, interspace 

 U-shaped, as wide as either horn. 

 Preorbital angles blunt, slighth^ pro- 

 duced. Basal joint of antenna with 

 two teeth, inner one nearly reaching line 

 of rostrum, the other smaller, on or- 

 bital border; besides, the orbit has four 

 tubercles on margin, two superior, much 

 smaller than external or inferior tubercle. 

 Lateral margin armed with five spini- 

 form teeth; the first obtuse, often bifid 

 at extremity; the second longer, sharp 

 and double, curving forward; third and 

 fourth more slender and about the same 

 length; fifth postero-lateral, much smal- 

 ler, and situated higher up on cara- 

 pace; in a transverse oblique line with 

 this spine are two tubercles or a spine and a tubercle. Subhepatic 

 region with two tubercles; a number of tubercles, some of them 

 pointed, are on the subbranchial and pterygostomian regions. Arm 

 with four or five spines on upper margin; two on inner margin; and 

 a few tubercles on the upper surface. Wrist smooth; inner margin 

 evenly rounded. Hand smooth; fingers narrowly gaping; a broad, 

 low tooth near the base of the dactylus. In young specimens the 

 tubercles of the carapace are more protuberant. 



Color. — Larger specimens nearly uniform deep brownish red or 

 terra cotta above, brighter on chehpeds, darker on legs (due to brown 

 hairs); legs often with brighter red bands at joints; under parts of 

 body mostly white or bluish white; legs red, specked with pale 

 yellow. (Verrill.) 



Fig. 



124. — Mithrax hispidus (171.'62), 

 maxilliped, x 7.6 



