PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 503 



narrowed to a truncated tip about a third as broad as the base. The 

 spiue upon the secoud segment of the peduncle below the articulation 

 of the scale is much shorter than in A. Agassizii. 



The oral appendages difi'er only slightly from those of A. Agassizii. 

 The mandibles are thicker and heavier, the opposing edges of the ven- 

 tral processes a little narrower, and their teeth fewer in number, thicV 

 and obtuse, and the terminal segment of the palpus is a little narrower. 

 The mandibles are in fact more like those of A. eximea. The fold on the 

 ventral side near the tip of the endopod of the first maxilla is armed, in 

 place of the two to four short spines in A. Agassizii^ with a series of ten 

 to twelve setse, of which the proximal are stout, and somewhat spini- 

 form, but the distal very slender. The two lobes of the distal segment of 

 the protognath and the endognath of the second maxilla are slightly 

 more slender than in A. Agassizii. The anterior lobe of the scaphognath 

 is much longer and narrower, contracted near the middle and slightly 

 expanded at the obtuse and somewhat truncated tip, while the posterior 

 lobe is slightly broader. The endopods and exopods of the maxillipeds 

 are much longer and more slender than in A. Agassizii, but these ap- 

 pendages do not differ in other respects. The propodus and dactylus 

 of the first gnathopod are a little more narrowed distally, and the line 

 of articulation between them slightly less oblique than in A. Agassizii. 

 The second gnathopods differ scarcely' at all. 



The perseopods are similar to those of Acanthephyra Agassizii, but 

 are a little more slender, somewhat less hairy, and the proportions of 

 the segments slightly different; the carpus in the second pair is nearly 

 as long as the merns and much longer than the chela, which is consid- 

 erably shorter and much more slender than in the first; and the carpi 

 in the third, fourth, and fifth pairs are relatively shorter than in A. 

 Agassizii. 



The first and second somites of the pleon are rounded above, but the 

 third and fourth are very strongly compressed dorsally and project in a 

 very high and sharp crest, highest at the articulation between the two 

 somites and on the third produced into a very long, slender, compressed, 

 and spiiiiform tooth which is arched over nearly or quite the whole 

 length of the fourth somite, which is itself without any cariual tooth. 

 The fifth and sixth somites are sharplj" carinated dorsally, but the carina 

 does not project in a tooth or spine on either. The pleura are of about 

 the same form as in A. Agassizii, but are somewhat less deep. 



The telson is very long and slender, only very obscurely sulcated 

 above, armed with seven or eight pairs of small dorsal aculei, and tipped 

 with three to five slender seines between a pair of much larger lateral 

 ones. 



The uropods and pleo})ods are nearly as in A. Agassizii, but the ovate 

 inner hrnelliform ramus of the first pleopod of the male is a little nar- 

 rower and the marginal stylet reaches slightly beyond the tip of the 

 lamella itself. 



