186 Bulletin, Vanderhilt Marine Museum, Vol. II 



Color: In life this crab has the upper surface of its body 

 and legs, except the second pair, which are purplish-blue, irregu- 

 larly mottled with light and dark grey, closely imitating the color of 

 the sand into which the crab frequently flattens itself to lie in wait 

 for its prey. 



Technical description: Young male: Carapace oval, nearly sub- 

 circular, 12 mm. long, 17.5 mm. wide from tip to tip of lateral spines ; 

 interorbital space 5.5 mm. wide ; frontal teeth four, shallow, broadly 

 rounded, the inner pair slightly narrower than the outer; the orbital 

 teeth also rounded, but smaller than the frontal teeth; the margin 

 sinuate but not bifid ; the lateral margin is armed with eight teeth, 

 all acute ; the second, fourth, sixth and eighth teeth are subequal and 

 are smaller than the alternating teeth ; the ninth or lateral tooth is but 

 very little longer than the others and is curved slightly forward. The 

 anterolateral margin of the carapace is fringed with setae. The post- 

 lateral and posterior margins are lightly carinate. There is a curious 

 mask-like figure outlined in areolations on the gastric region. The 

 areolations of the carapace are sharply defined and the transverse 

 ridges have sharp, granulose edges. The depressed areas are finely 

 pubescent. 



The chelipeds are very long in the adult, much less so in young 

 specimens; the merus has five, occasionally six, unequal spines on its 

 anterior margin, none at the posterior distal angle; the carpus has 

 strong spine at the inner angle, a shorter one at the outer angle ; three 

 interrupted granulate carinae on the upper surface ; the palm is high, 

 longer than the fingers, with five longitudinal, granulate carinae, the 

 uppermost of which terminates in an acute, subdistal tooth. The 

 fingers are grooved, subequal, the upper right one with a large, sub- 

 basal tooth. 



The ambulatories are very slender, the first pair exceeding the 

 others; all have the three distal segments heavily fringed with setae 

 on the lower margins. 



The natatory legs have no spines, the dactyl is oval. 



The eyes are large, reniform. 



The antennulae are extremely slender and fold transversely. 



The basal joint of the antennae has the inferior distal angle pro- 

 duced into a very short, bluntly rounded node. 



The external maxillipeds have the ischium short, rectangular, the 

 merus narrow, its inner distal angle but little excavate, the distal mar- 

 gin only slightly rounded ; outer face of both densely setose. 



