South African Crustacea. 263 



maxilliped with broad sti-aight exopod carrying a flagellum ; the last 

 two joints of the endopod invested with many long setae and spines. 

 The third maxillipeds with narrow flagellate exopod. Third joint of 

 endopod fringed with teeth ; this joint longer than the fourth, but 

 shorter than the sixth, which with its neighbours at either end is 

 clothed with elongate setae. First peraeopods (chelipeds) of female 

 much shorter than the ambulatory limbs, but longer than the slender 

 minutely chelate fifth peraeopods. 



The generic name is derived from in-aTias, soft, and TTTV, a fold. 



HAPALOPTYX DIFFICILIS, n. sp. 



Plate CV. 



The name dfficills is given to this species because with some 

 remarkable features which undoubtedly belong to it there are com- 

 bined others which occasion considerable perplexity. Of the five pairs 

 of peraeopods only the last pair were observed still in attachment to 

 the body, though along with it were a pair of chelipeds and four 

 elongate spinose ambulatory limbs. Together with this assemblage 

 there occurred a small square-bodied Megalopa with narrow pleon and 

 three small detached peraeopods. 



Beside the rostral spine the membranaceous carapace has on each 

 side a spine over the base of the eye-stalk and another at each antero- 

 lateral angle, with a small submarginal spine between the autero- 

 lateral and the supra-ocular. From the front the carapace widens 

 with a long curve to the base of the second peraeopod, thence bending 

 inward so as to leave exposed the bases of the third and fourth pairs, 

 and by an angular emargination of the hind border disclosing the first 

 segment of the pleon. On the infolded sides of the carapace there 

 are some prickles not visible in dorsal view. 



The eye-stalks are rather stout with dark dilated corneae. The first 

 antennae have a broad basal joint carrying a trifid spine, the second 

 joint much narrower but longer, the third nearly as long as second 

 and first combined, longer than the setose flagellum ; the accessory 

 flagellum very small. The second antennae have the terminal joint of 

 the peduncle long and slender with a fine-drawn six-jointed flagellum 

 ending in a long, very thin spine. 



The mandible is a broad blade without teeth or serration, carrying 

 a stout three- jointed palp, of which the third joint has four setules 

 at the apex. 



Between the first and second maxillae there is a rather close 

 resemblance apart from the latter's possession of the usual vibratory 



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