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



The telson (fig. 8z) is long, narrow, and tapering ; it is longitudinally angulate in the 

 dorsal centre and laterally compressed, the angle formed by the lateral compression being 

 armed with three minute spinules, and the distal extremity with several small spines. 



The ophthalmopoda (fig. 8a) are too stout at the base to be defined as pear-shaped. 

 They are rather oblong, with the ophthalmus a little broader in diameter than the 

 peduncle, and furnished with an imperfect ocellus that is connected with the ophthalmus 

 laterally. 



The first pair of antennae has two flagella that are subequal in length with the 

 carapace ; the upper is much more robust than the lower, and has the inferior margin 

 narrow and thickly fringed with membranous cilia. The peduncle is three-jointed; the 

 first joint is excavate to receive the ophthalmopod, and is furnished with a stylocerite 

 that is subequal in length with the joint that carries it, and abruptly terminates in a 

 sharp point ; on the outer margin, at the posterior extremity of this joint, a process which 

 is surmounted by a small tubercle crowned with hairs rises perpendicularly and projects 

 between the outer canthus of the orbit and the first antennal tooth on the margin of the 

 carapace, and there has the power, on the elevation of the antennae, of being locked and 

 supported by the short rigid antennal tooth, which stands on its outer side. 



The second pair of antennae carries a slender flagellum that is subequal with the length 

 of the animal. The scaphocerite is about three-fourths the length of the rostrum ; it is 

 sharp-pointed and the squamous portion tapers to the apex, where it is reduced to a 

 minimum, a circumstance that increases the efficiency of the organ as a weapon of offence, 

 for which purpose it is rendered more effective by the manner in which it is supported in 

 position by the teeth on the basal joint. 



The oral organs have not been examined in this species, since there is only a single 

 specimen in the collection. 



The second pair of gnathopoda reaches nearly to a level with the tooth on the under 

 surface of the rostrum, it is fringed with small hairs on the inner margin and obliquely 

 truncate at the apex, where it is tipped with small spines. 



The pereiopoda are rather short, averaging a length that is subequal with the 

 carapace, they are moderately robust and fringed on the posterior margins with hairs. 

 The first two pairs are subequal with the others and have a long and narrow chelate hand, 

 the fingers of which are subequal and about half the length of the palm. All the 

 appendages, more especially the posterior, are brought close together in the median line, 

 those on the two sides being in close contact. 



The pleopoda are moderately long and robust. They possess a long, stout, laterally 

 compressed basal joint that stands upon a rigid prominence, attached partly to the ventral 

 surface of the pleon and partly to the inner wall of the coxal plate. The first pair has 

 the branches unequal, in the only specimen of this species ; the outer ramus is long, 

 narrow, flexible, and rapidly tapering ; the inner is short, almost rudimentary, and 



