Boone, Crustacea, Cruises of "Eagle" and "Ara," 1921-28 95 



movable article, a strong, acuminate, obliquely outward directed one 

 at the external angle which is half as long as the rostrum and a 

 smaller one on the inferior orbital border; the first and second free 

 articles are stocky, subequal, each equivalent to one-third the length 

 of the rostrum, beside which they lay; the flagellum is very slender, 

 about two and one-half times as long as the rostrum, each ring fur- 

 nished with exceedingly long setae. 



The antennulae are fleshy and fold a little obliquely within the 

 fossett. 



The eye is exposed, large, convex, brown; a strong fringe of setae 

 surrounds the cornea ; the superior orbital margin has, in addition to 

 the pre- and postorbital teeth, two lesser ones, one on each side of the 

 suture line. 



The external maxillipeds have the outer distal lobe of the merus 

 produced and broadly rounded. 



The chelipeds are strong, slender, reaching beyond the rostrum 

 when extended, the merus has two longitudinal rows of spines on the 

 upper surface; the carpus is very spinous; the propodus in larger 

 specimens has a few spines basally ; the fingers have a short gape, the 

 cutting edges crenulate frequently, but not always, with one large 

 sub-basal tooth on the dactyl. 



The ambulatories are slender, the first pair as long as the chelipeds, 

 the others decreasing slightly in length, each with two rows of spines 

 on the upper surface of the meral and carpal joints ; the dactyl very 

 curved with a sharp tip. 



Synonymy. — Mithrax acuticornis Stimpson, Bull. Mus. Comp. ZooL, 

 vol. 2, p. 116, 1870. — A. Milne Edwaeds, Crust. Reg. Mex., p. 98, 

 1875.— Rathbun, Bull. U. S. Fish. Comm., vol. 20, pt. 2, p. 66 

 part) for 1900 (1901). — ^A. Milne Edwards and Bouvier, E. L., 

 Mem. Mus. Comp. ZooL, vol. 47, p. 390, pi. 11, fig. 11, text figs. 

 22, 23, 1923.— Rathbun, Bull. 129, U. S. Nat. Mus., p. 388, pi. 

 136, figs. 1 and 2, pi. 257, fig. i, 1925. 



Nemausa rostrata Milne Edwards, Crust Reg. Mexico, p. 81, pi. 17, 

 fig. 4, 1875. 



Mithrax (Nemausa) acuticornis Rathbun, Proc. U. S. Nat. Mus., vol. 

 15, p. 260, part, pi. 37, fig. 1, 1892. 



Mithrax (Mithrax) acuticornis Stimpson, variety Rathbun, Bij- 

 dragen tot de Dierkunde, Artis Magistra te Amsterdam, Aflev. 23, 

 p. 20, 1924. 



