816 THE VOYAGE OF H.M.S. CHALLENGEE. 



Phoxocephalus kergueleni, n. sp. [Phoxus kergueleni, PI. LV.). 



The rostral part of the head projecting with a tolerably sharp apex over the peduncle 

 of the upper antennae ; the first three segments of the pleon each longer than any 

 segment of the perseon ; their postero-lateral angles rounded, the lower border of the third 

 long and for the most part straight. 



Eyes small, distant, in the spirit-preserved specimens not dark, with few ocelli. 



Upper Antennae. — First joint considerably longer than the next two united, its 

 breadth little less than its length, distally a little outdrawn on one side ; second joint 

 longer and broader than third, each of a length about equal to its breadth ; the flagellum 

 of five articulations ; the first equalling in length the last of the peduncle and also the 

 last of the flagellum ; the secondary flagellum of three joints, the three together equalling 

 the first two of the primary. 



Lower Antennse. — First joint not much expanded, gland-cone obscure, seemingly 

 with a broad apex, third joint not very short, the fourth broad, with marginal setse and 

 apical and surface spines ; the fifth half the length of the fourth in the male, more than 

 half in the female, expanding distally, broader in the male than in the female ; the 

 flagellum in the male specimen examined had fifteen joints, moderately thick, with 

 quite inconspicuous cilia, except two short ones on the tip of the last joint; in the female 

 this flagellum had five slender joints. 



Upper Lip. — The broad apical border slightly emarginate. 



Mandibles. — Similar to those of Phoxocephalus hassi; the cutting plate, however, here 

 on both mandibles showing both above, below, and on the oblique margin a certain amount 

 of dentation, one tooth below being prominent and large, especially on the right mandible; 

 the secondary plate of the left mandible has its margin divided into five teeth ; on the 

 right mandible it has two sharp teech below and a row of denticles above ; the spine- 

 row of each mandible contains three curved spines ; the palp, as in Phoxocephalus 

 hassi, is much longer than the trunk ; its third joint in the male was as long as the 

 second, but in the female not so long ; there are three or four spines along the upper 

 part of the inner margin of the second joint, and nine on the apical part of the third 

 joint. 



Lower Lip small and compact, with the mandibular processes seemingly less divergent 

 than in Phoxocephalus hassi. 



First Maxillse. — Inner plate oval, smooth ; outer plate short, with seven spines on 

 the rather oblique apical margin, the spines similar in character to those of Phoxocephalus 

 hassi; the one-jointed palp narrow, but little overtopping the outer plate, with four long 

 setae on the apex. In having seven spines on the outer plate this species agrees with 

 Kr0yer's account of Phoxus holbolli. 



Second Maxillse. — The outer plate extending a very little beyond the inner, each 



