358 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Localities subsequently reported, with collectors: Mexico: T. B. 

 Wilson (Rathbun) ; Mazatlan, Sinaloa, A. Agassiz (Rathbun) ; Puerto 

 Angel, Oaxaca, C. R. Orcutt (Rathbun, holotype of Mithrax (Mith- 

 rax) orcutti). Nicaragua: Corinto, Zaca (Crane). Panama, Capt. Field 

 (Rathbun). [All the foregoing as Mithrax (Mithrax) orcutti Rath- 

 bun.] 



Atlantic analogue: Mithrax (Mithrax) hemphilli Rathbun. 



Diagnosis: Rostral horns of moderate length, tips acute, incurving. 

 Four blunt anterolateral spines, the first or hepatic with an auxiliary 

 spine at its base. A tubercle near the proximal end of the outer surface 

 of the manus. Propodites of ambulatory legs without spines. Tip of male 

 pleopod pointed, three subterminal folds. A large species. 



Description: Carapace, including spines, a little longer than wide; 

 granules and tubercles numerous, high and very unequal. Spines of the 

 dorsum arranged as follows: one on each epigastric lobe; a transverse 

 row of four on protogastric lobes; three median mesogastric; one urogas- 

 tric; a line of three on the cardiac region forming a transverse curve 

 concave forward ; behind these, one on median line ; from seven to eight 

 on branchial region; four on intestinal region forming a transverse curve 

 concave to posterior margin ; posterior marginal spines of the intestinal 

 region prominent and not continuous with the spines at the extremity of 

 the curved row above. Rostral horns moderately long, the tips curving 

 inward and acutely pointed. Orbital teeth or spines blunt pointed, the 

 one at the outer base of the preorbital spines minute or obsolescent. Of 

 the four anterolateral spines, also blunt, only the first having a secondary 

 spine on its anterior base ; at the middle of each of the succeeding sinuses 

 a small and insignificant spine or tubercle. The first or hepatic spine on 

 a lower level than the others. The fourth spine, at the lateral angle of the 

 carapace, rather far forward ; between it and the large posterolateral spine 

 a smaller, slenderer spine. On the subbranchial and subhepatic regions a 

 row of seven or eight spines extending forward from the lateral angle of 

 the carapace to the angle of the buccal cavity. On the basal antennal seg- 

 ment, the spine at the anteroexternal angle the largest and rather near 

 the margin ; a smaller spine on the orbital margin and one at the base of 

 the next segment ; this last spine at the end of a tuberculated ridge border- 

 ing on the antennular fossa. 



Chelipeds of male stout, longer than first ambulatory leg; merus with 

 two rows of long spines above and numerous tubercles elsewhere ; carpus 

 armed with high, granulated knobs; hands smooth except for a large 

 tubercle on outer surface near proximal end and in the middle of its 



