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



Mithrax (inclnding Mithraculus). 



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

 (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 haivy. 



Spines of manus in two dorsal rows connitus 



B'. Manus smooth, without spinules. 



C. Eostral horns short, blunt or tuberculiform. 



D. Spines or tubercles of antero-lateral margin four, behind orbitals, simple or 



bifid : basal joint of antennae with inner tooth longest. 



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



peds multispinose; basal joint of antennee narrow, with two denticles. /iisptdtts 

 E'. Carai^aee and carpus of chelipeds tuberculate ; merus spinose ; rostral horns 



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



acute spines --- - {depress iis) 



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 (hirtipes) 



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. 



Figure 38. 



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

 only Bermuda specimen known is young. 



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

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

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

 especiall}' 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 sti'ong dark 

 colored hairs. 



In both species the raerus 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. 



