COPEPODA 



87 



thorax, but in others it is scarcely one third. The comparative length of the abdominal somites and 

 the furcal rami are 32 — 24 — 18 — 11 — 16; the furcal rami are r6 as long as wide. The receptacula 

 seminis are in most specimens well developed, and of similar shape as in Ch. obhisifrons (text-figs 22 b — c). 



The antennulae, which have the segment 24 and 25 well separated, reach about to the end 

 of the third abdominal somite; the segment 2 is i*a as long as 8^9, which is a little shorter than 

 the segment 20; the segment 21 is about as long as 18, and the segment 23 is n as long as the 24. 

 The appendages are like those of Ch. obtusifrons^ but a distinct "Aestetask" is found in segment 7; the 

 posterior seta of segment 23 reaches distinctly beyond the end of segment 25. The antennae are like 

 Sars' figure, with the Re 14 as long as the Ri; the setae of Re I — II are arranged as described in 

 Ch. modestus. The mandibulae are like Sars' figure. The maxillulae are in main features, especially 

 in the number of setae, like Ch. armatus; the maxillae are b 



scarcely different from S a r s ' figure, but differ from those of 

 mentioned species by a small depression in the middle of 

 the exterior margin of the first basipodite, which seems to 

 be connected with a wide chitinous sac. The third basipodite 

 of the maxillipeds, is 1-5 as long as the first and second seg- 

 ments and almost twice as long as the endopodite. 



In the first pair of legs the Se Re I extends 

 distinctly beyond the end of Re II. The second pair of 

 legs has the first basipodite greatly enlarged inwards; the 

 articulation between Ri I — II is wanting anteriorly; glan- 

 dular pores are present at the base of the Se in Re I — III; 

 the St has 58 spinules (in Sar's figure 35 only). The fourth 

 pair of legs differs from that of the three first pairs by 

 wanting marginal row exteriorly of the second basipodite; its structure is in most features like Sars' 

 figure, and the St has about 60 spinules (text-fig. 22 d). 



The anterior surface of the labrum was like that of Ch. armatus, but differed by the wanting 

 lateral irregular group of hairs in front of the transverse series. The oral surface has the hairs in 

 the three first groups, especially the third, somewhat differently arranged, as seen in fig. 6 a; the groups 

 4—5 are more irregular than in this species. The lamina labialis is, as seen in fig. 6 b, in most respects 

 similar to that of Ch. armatus; the inner longitudinal series in front of the lamina was not observed. 

 The longitudinal series of hairs upon and behind the labial lobes are in most features, especially in 

 series lateral IV — V, like those fully described in Ch. obtttsifrons. 



Text-fig. 22. Aetidiopsis rostrata G. O. Sars. 

 a. Head in lateral view X 60. b. Genital somite 

 in lateral view X 60. c. Genital area from below 



X ii5- d. Pes IV dest. in post, view X 60. 



Occurrence. The Ingolf Expedition ir / 7 96 6-30 p. m. St. 105 65°34 L,. N. 7°3i L,. W. closing 

 net 700 fathoms has taken a single adult female, and the S/S Thor has gathered it at the following 

 three stations. 



20 / 6 04 St. 153 65°20 L. N. 27°i2-5 L. W. Yt. 800 M. Wire 1 f ?. 

 2I / 6 04 St. 154 65°27 L,. N. 27°io I* W. Yt. 800 M. Wire 3 f ?. 

 22 / 7 04 St. 214 67°±9 L. N. i7°55 L-. W. Yt. 800 M. Wire 6 f $. 



