Boone, Crustacea, Cruises of "Ara" and "Alva" 245 



Technical description : In the field this species is readily 

 distinguished from Cardisoma carnifex (Herbst), which is found 

 in the same regions, by the rich violet-purple colouration of the 

 carapace and the bright cinnabar red of the chelipeds of Cardi- 

 soma hirtipes Dana. 



The characters which distinguish Dana's hirtipes from the 

 older Herbst species C. carnifex^ are the following : 



I. The carapace of Cardisoma hirtipes is noticeably less con- 

 vex, the regions are more sharply defined by deeper, wider grooves ; 

 this is especially apparent in the gastric region, where the grooves 

 divide it into three areolae, a median and two lateral, the smaller 

 hepatic lobes, outside the latter, being similarly circumscribed; 

 on the sides of the epibranchial regions there are some fine, 

 oblique striations. 



II. The greatest width of the orbital cavity of hirtipes is from 

 three-fifths to two-thirds of the length of the orbital cavity ; the 

 inner margins of the orbit, formed by the deflected sides of the 

 front of the carapace, are not nearly so oblique; the superior 

 orbital margin is less sinuous and extends slightly forward and 

 downward, uniting with the external orbital angle. The basal 

 antennal joint is smaller and does not touch the front. 



III. The buccal cavern is longer than wide, the width meas- 

 ured across the middle of the meral articles of the external maxil- 

 lipeds being only 0.8 of the length of the cavern measured in the 

 median line. 



IV. The inequality of the chelipeds is decidedly less in C. hir- 

 tipes; the chelipeds being more frequently equal than unequal, 

 even in the large old specimens, which usually have the palms 

 enlarged and the related dactyli long. 



V. The ambulatory legs are more abundantly furnished with 

 tufts of stiff bristles which occur along the entire anterior mar- 

 gin of the merus. 



VI. The male abdominal belt of C. hirtipes has the distal (sev- 

 enth) somite more than 0.5 as long in the median line than the 

 preceding (sixth) somite in the present specimen from Kusai 

 Island. 



The carapace is convex longitudinally, five-sixths as long as 

 wide, the regions sharply defined by deep grooves, the areolae 



'Recently redescribed and figured in Vol. \', Bull. Vandeibilt Marine Mus. 1934, p. 187, pis. 

 97, 98. 



