400 .4. E. Verrill — Decapod Crustacea of Bermuda. 



Mithrax (including Mithraculus). 



Analytical Key to the Bermuda Species of Mithrax and some allied species 

 (Modified from that of Miss Eathbun). 



A. Carapace without oblique, parallel, branchial grooves. 



B. Manus of chelipeds spinulose. Carapace with conical spines ; not setose. 



a, Two distal segments of ambulatory legs stout, very setose ; spines of 

 manus in one dorsal row spinosissimus 



a'. Two distal segments of ambulatory legs long and slender, sparsely hairy. 



Spines of manus in two dorsal rows eonuitus 



B'. Manus smooth, without spinules. 



C. Rostral hoins short, blunt or tubereuliform. 



D. Spines or tubercles of anterolateral margin four, behind orbitals, simple or 



bifid : basal joint of antennae with inner tooth longest. 



E. Carapace not multi-tuberculate; carpus often nearly smooth ; merus of cheli- 



peds multispinose; basal joint of antenn;? narrow, with two denticles. ^ispj'dies 

 E'. Carapace and carpus of chelipeds tuberciilate ; merus spinose ; rostral horns 



about as long as broad, obtuse ; basal joint of antennje wider, with two 



acute spines {depressas) 



C Rostral horns long and slender acuticornis 



A'. Carapace with oblique, parallel, branchial grooves ; antero- lateral margins 



with four acute spines; carapace broader than long in adults ./orceps (hirtijies) 



Mithrax cornutus Saussure. Coral Crab, Bed Spider Crab. 



Mithrax cornutus Saussure, Mem. Crust, nouv. Mex. et Antilles, p. 7, 1858. 

 A. M.-Edw., Miss. Sci. Mex., v, i, p. 97, pi. xxii, 1875. 



FiGUBE 38. 



This species grows to rather large size in tlie West Indies. The 

 only Bermuda specimen known is j'oung. 



It closely resembles 31. spinosissimus of the West Indies* in the 

 form and spinulation of the carapace and chelae, hut it can easily be 

 distinguished by the longer and more slender chelipeds and legs, and 

 especially by the far more slender distal two segments of the ambu- 

 latory legs, which are nearly destitute of spines and have only 

 short, sparse hairs, while in the latter these segments are stout, not 

 abruptly attenuated, and are thickly covered with strong dark 

 colored hairs. 



In both species the merus and carpus of the chelipeds are covered 

 with numerous strong and acute curved spines ; in this species the 

 merus is longer and has about eight or nine very acute spines on the 

 posterior border, and near them another irregular row of nearly the 



* This species is likely to occur on the rough grounds outside the Bermuda 

 reefs. Hence I have given the most obvious distinctions here. 



