86 



COPEPODA 



The shape of the body is like Farran's description; the anterior division is 2-9 as long as 

 the abdomen; the furcal rami are 1-4 as long as wide (text-figs 21 a— b). The antennulae differ from 



those of Ch. obtitsifrons by the 20 segment, which is a little longer 

 than the second, which is again longer than segments 8^9. The 

 Si 1 of the third basipodite of the viandibulae is longer and thicker 

 than that of Ch. obtitsifrons, but shorter than that of Ch. Poppei. 

 In the other mouth appendages scarcely any difference was ob- 

 served. In the first pair of legs the Se Re I does not extend to 

 the end of the segment. The segmentation of the legs is better 

 developed than in Ch. obtitsifrons, as shown by Far ran (text-figs 

 21 c— d). 



Occurrence. Though the Thor has only taken 3 f$ (of 

 which one with spermatophor) 8 /e 1905 St. 72 S7°57 ^- N. 9°53 

 L,. W. Yt. 1500 M. Wire, I think that this species belongs to the 

 fauna of the region explored by the Ingolf Expedition. 



Remarks. This species is according to Far ran fairly 

 common on the west coast of Ireland ; its range was from 280 to 1000 fathoms. I think it is extremely 

 doubtful whether the species which A. Scott refers to this species, from the Malayan Sea, really is identical 

 with the Irish species. I think that Farran is right in regarding it as a species which forms a con- 

 necting link between the much smaller Ch. Poppei and the much bigger Ch. obtusi/rons, of which the 

 former is a distinct Arctic and the latter a Mediterranean form. 



As the females belonging to the Chiridius, as Giesbrecht defined it are very much alike, a 

 thorough investigation of the differences between the existing species viz. those from the Siboga 

 expedition, the three mentioned above and Ch.polaris Wolf. (p. 212), which is very nearly related to 

 if not identical with Ch. gracilis, is needed. 



Text-fig. 21. Chiridins gracilis Farran. 



a. Genital somite in dorsal view X 60. 



b. Furca X 60. 



c. Pes II sin in anterior view X 60. 



d. Pes III sin in anterior view X 60. 



21. Aetidiopsis rostrata G. O. Sars. 

 (PI. II figs 6 a — b ; text-figs 22 a— d). 



1903. Aetidiopsis rostrata n. sp. G. O. Sars, p. 160, supplement 



pis. IV— V. 



1904? Faeroella multiserrata n. sp. Wolfenden, p. 117, pi. IX 



figs 26 — 28. 



1906? — Wolf. Pearson, p. 13. 



1907. Aetidiopsis rostrata G. O. Sars. Koefoed & Damas, p. 409. 

 1908? Faeroella multiserrata Wolf. Farran, p 29. 



1908. Aetidiopsis rostrata G. O. Sars. v. Bremen, p. 33, fig. 35. 



1909. Nee. — — — A. Scott, pp. 40—41, pi. 



V figs 13—24. 



Description. f$. Size: Specimens from Thor St. 214 measured 3-8 mm.; anterior division 276 

 mm.; urosome 1-04. Other specimens measured 3-4 and 3-9. Sars' specimens measured 4-4 and Wolf en- 

 den's 3-54 mm. 



The shape of the body is like Sars' figure. The rostral spines (text-fig. 22a) are comparatively 

 shorter, and in shape somewhat different from Sars' figure; the frontal organ is very prominent. The 

 articular membrane is distinct not only dorsally, but also laterally between the head and the first 

 thoracic somite. The lateral spines of the thorax (text-figs 22 b) scarcely reach the middle of the 

 genital somite. The abdomen is in most specimens at least one third of the length of the cephalo- 



