NO THE VOYAGE OF H.M.S. CHALLENGER. 



The telson is quadrate, with the base calcareous, longer at the sides than in the 

 median line, posterior margins fringed with small teeth ; posterior division membranous. 



The ophthalmopoda are short and thick and united to the membranous somite by a 

 narrow articulation. 



The first pair of antennae is smooth, slender and cylindrical. The first joint is the 

 longest, the second the shortest, and the third is but little longer than the second ; the 

 terminal flagella are nearly as long as the peduncle, and together they equal the cara- 

 pace in length. The entrance to the acoustic apparatus is by a diagonal fissure, 

 protected by small hairs, on the upper surface at the base of the first joint. 



The second pair of antennas is a little longer than the entire animal. The first joint 

 of the peduncle is fused with the metope, the second joint has oidy one sharp tooth 

 below and two above, one being on each side of the posterior articulation ; on the inner 

 side an efficient stridulating organ exists (fig. c). The third joint is armed with several 

 sharp teeth on the upper surface, but none that are important on the lower. This is also 

 true with regard to the fourth joint. The flagellum is long, rigid, slender and tapering, it 

 is armed with spines or sharp teeth situated in longitudinal and transverse rows, those on 

 the upper surface are both larger and closer together than those on the lower. 



The oral appendages correspond with those of the genus generally. 



The pereiopoda are simple in structure and uniform in character ; the first pair is the 

 most robust, the second is the longest, the others gradually decrease in length and thick- 

 ness. The dactylos of the anterior pairs is furnished with a thick brush of hairs that is 

 continued in a couple of rows of fasciculi of the same character on the under surface of 

 the distal extremity of the propodos. 



In the female the posterior pair is peculiarly chelate. The propodos has a pollici- 

 form process developed at the lower distal angle, which antagonises a similar process 

 developed at the base of the lower surface of the dactylos ; the two form a small but 

 efficient chela, while the dactylos proper is produced as in the preceding, from which it 

 differs only in being smaller in a proportion corresponding with those anterior to it. 



In the male the anterior three pairs have the upper distal extremity of the meros 

 unarmed, and the last two furnished with a strong tooth. 



In the female this tooth exists on all the pereiopoda, At the base of the first or 

 coxal joint, close to the articulation with the plastron, is the foramen of the oviduct, 

 which is very minute. 



In the male the posterior pair of pereiopoda possesses in the same situation a large 

 opening that is increased in size by the nearer portion of the joint being enlarged into a 

 process projecting on the inner side. 



In the male there are two small calcified tubercles on each side of the median line at 

 the posterior margin of the pereion, which are absent in the female. 



There are no pleopoda attached to the first somite, while each of the four following 



