4 THE VOYAGE OF H.M.S. CHALLENGER. 



The hepatic area is comparatively smooth and very convex, while the subhepatic 

 region is somewhat excavated, densely pubescent, and armed with two rounded tubercles 

 on its outer border. The pterygostomial area is pubescent, the inner part almost 

 membranous in consistence. The orbital border is furnished with a single prominent 

 tooth above, placed external to the lateral spine of the rostrum, and the inferior border 

 ends in a somewhat larger and more conical process. The eyes are small, and when 

 retracted almost completely hidden in the deep orbits ; the basal joints of both pairs 

 of antennje are robust, and the terminal joints of the internal pair are folded in the 

 orbital cavity ; the flagellum of the external antenna is short. The external maxillipedes 

 have the ischial and meral joints subequal, the exognath is moderately stout and 

 reaches almost to the end of the merus ; the ischium is crossed by an oblique elevation 

 which passes on to the exognath and then becomes continuous with the outer border 

 of the subhepatic region. These lines on either side form the sides of a triangle which 

 is completed by the ciliated line stretching across the front of the carapace, and includes 

 within its boundaries the eyes; the antennular, and antennal segments, the subhepatic 

 regions, and the upper part of the buccal cavity ; the whole being densely ciliated. 



The chelipedes are moderately ' long and furnished with a thick clotlijng of hairs, 

 the tips of the fingers alone being naked ; when these hairs are removed, the joints 

 are found to be smooth. The propodus is longer than the carpus and smooth, with its 

 finger strongly toothed and slightly excavated ; the dactylus is also toothed, and its free 

 end fits into the space between the two terminal teeth on the finger below. The carpus 

 has a prominent conical tooth on its upper border, and a similar yet larger projection 

 towards the upper part of the antero-external border ; towards the posterior border 

 of the carpus there exists a well-marked fringe of hairs which (when the chelipedes 

 are folded in) is directly continuous with that on the carapace. The merus is somewhat 

 trigonal, and more sparingly pubescent. The first and second pairs of ambulatory limbs 

 are equal in length to the chelipedes, and have the penultimate and antepenultimate 

 joints clothed with long hairs as well as the lower borders of the meri ; the latter 

 joints are trigonal, with the anterior and posterior surfaces smooth and polished. The 

 dactyli are long, and each ends in a sharp curved claw which is yellowish in colour. 

 The third pair of ambulatory limbs are shorter than usual, with the merus and carpus 

 subequal, and the short, curved, horny dactylus is opposed to a similar process of the 

 propodus ; two small spines are noticeable on the latter joint immediately over the 

 attachment of the dactylus. The fourth pair of ambulatory limbs are more than half 

 as long again as the preceding pair, they are subdorsal in position, and flattened against 

 the sides of the carapace ; the merus is nearly twice the length of the carpus, and the 

 terruinal claws, though resembling those of the third pair, are slightly less curved. 



The abdominal segments are seven in number, the fourth, fifth, and sixth with a 

 well-marked depression on either side of a rounded median elevation ; the last four 



