r 



THE SPIDER CRABS OF AMERICA 131 



Range. — From Cape Lookout, North Carolina, to Florida Straits, 

 Gulf of Mexico (west coast of Florida) and Yucatan Channel. 

 Depth, 15 to 200 fathoms. 



Material examined. — See table, page 132. 



PYROMAIA ARACHNA Rathbun 



Plates 42 and 43 



Pyromaia cuspidata Rathbun, Proc. U. S. Nat. Mus., vol. 17, 1894, p. 73 



(part); not P. cuspidata Stimpson. 

 Pyromaia arachna Rathbun, Proc. U. S. Nat. Mus., vol. 64, art. 14, 1924, 



p. 1 (type-locality. Gulf of Mexico, SW. of Cape San Bias, Florida; 



169 fathoms; station 2400, Albatross; male holotype. Cat. No. 18144, 



U.S.N.M.). 



Diagnosis. — Three spines on branchial margin. Five median spines 

 on carapace. Rostral spine slender, acuminate. Manus of male 

 cheliped elongate. An erect spine near proximal 

 end of merus of ambulatory legs; a fringe of 

 hair on each side of dactylus. 



Description. — Adult male: In form, strongly 

 resembles cuspidata. Five median spines on car- 

 apace, no urogastric spine. Three marginal spines 

 on branchial regions; these are exclusive of the 

 spine above postero-lateral margin. Spines 

 more slender than in cuspidata, the posteri.or 

 gastric, anterior cardiac and intestinal spines 

 being longest. The fine granules of the carapace 

 are further apart than in cuspidata, and the in- 

 terregional depressions are, to some extent, 

 smooth. Rostrum more ascending than in fig49.— pyromaucuspidata 

 cuspidata, and longer, between one-third and one- 3 75^^^ maxilliped, x 

 fourth the postrostral length of carapace; it is tri- 

 angular at base, then abruptly narrows into a slender spine, having 

 usually two enlarged spinules above. The spine on outer margin of 

 basal article of antenna is situated near the posterior end instead 

 of at the middle. 



Chelipeds and ambulatory legs naked, surface rougher than in 

 cuspidata. Chelipeds less stout, margins spinous; manus swollen, 

 but much narrower than in cuspidata, the length along upper margin 

 twice as great as height, which slightly exceeds thickness; gape at 

 base of fingers very narrow. An erect spine at proximal end of merus 

 of legs, distal spine a little longer than in cuspidata; a thick fringe of 

 short hair on each side of dactylus. Spine of first abdominal segment 

 longer than in cuspidata. 



Adult female: Chelipeds not much stouter than ambulatory legs. 

 All dorsal spines are reduced in size except the long abdominal spine. 



