SPIDER CRABS. RATHBUN. 11 



Chelipeds as long as carapace ; ischium subspherieal, viewed 

 from below : inerus armed with three spines above, the terminal 

 spine not in line with the other two ; carpus elongate ; -smooth; 

 manus longer than inerus, compressed, distally tapering, 

 fingers slender, gaping, distal half of prehensile edges crenulate, 

 a lowtooth on proximal half of dactylus. 



First ambulatory leg of enormous size, over twice as long 

 as carapace and correspondingly stout ; a short, blunt spine 

 at lower, distal end of ischium ; next three articles rough with 

 low tubercles or nodules ; dactylus longer than propodus, 

 compressed. 



The legs diminish in length and stoutness from the first to 

 the fourth : the last three pairs are nearly smooth ; the 

 dactylus is distinctly shorter than the propodus ; the second 

 leg is much stouter than the third and fourth. 



Female. The carapace is wider anteriorly in proportion 

 to the length than in the male, the ''neck being shorter 

 and less conspicuous ; the aiitennal spine is slenderer and 

 more outstanding, the post-orbital spine is slenderer and is 

 directed obliquely forward a little, the anterior of the hepatic 

 spines is longer, slenderer and hooked inward a little at tip. 

 The rostral horns are broken off near the base and are missing, 

 but the stumps appear narrower and less flat than in the male. 

 The posterior hump is slightly developed and overhangs the 

 posterior margin of the carapace but little. Chelipeds slender, 

 especially the chelae ; arm with various tubercles above in 

 addition to the three spines of the male : chelae almost 

 filiform, the horizontal fingers less than half as long as palm, 

 and narrowly gaping in basal third only. The first ambu- 

 latory leg is estimated at no more than twice as long as the 

 carapace ; dactylus a trifle longer than propodus, both 

 measured along the dorsal line. The second ambulatory leg 

 is not so much stouter than the third as in the niaie ; in the 

 .second, third and fourth legs there is more difference in the 

 length of dactylus and propodus than in 1 he corresponding 

 .articles of the male. 



Genus NAXIA, Leach. 

 NAXIA ARIES, Ouerin. 



Halimus aries, Latreille. in Guerin, Icon. Regne Auim., ii.. 

 Crust, pi. ix., figs. 2, 2a-c. Milne Edwards, Hist. Nat. 

 Crust., i., 1834, p. 341 ; Cuvier's Regne Anim., Crust.. 

 Atlas, 1849 (fide McCulloch), pi. xxviil, figs, ;>, "2a-c. 



Halimus gracilis, Baker, Trans. Roy. Soc. S. Australia, xxix., 

 1905, p. 124, pi. xxiii.. figs., 4, 4o. 



