COPEPODA j 5I 



The first segment of the left exopodite is fairly long and slender, while the second, as shown in text- 

 fig. 41 f, is broad and widened out terminally, where a bifurcate spine is seen; the third segment (PL V 

 fig. 7 a) is distinctly widened out towards the end and produced inwards, where the usual tuft of mar- 

 ginal setae is observed; on the posterior surface groups of delicate hairs are found. Inwards at the 

 base of Re III, a partly independent, lobe is observed with groups of fairly long hairs posteriorly. 



The outline of the labrum is, as seen in fig., very similar to that of the female, but the whole 

 apparatus is soft-skinned without any setae, but adorned with an intricate systeme of chitinous ridges; 

 two labial lobes are present with a longitudinal furrow between. 



Parasites. In one specimen twisted structures like those described in Gaidius tenuispinus 

 (p. 92) were attached behind both maxillae; in another specimen a similar organ was found behind 

 the one maxilla only, but in that specimen a "sac-shaped parasite?" was found attached to the I4 I 

 of the left maxillula. 



Occurrence. The Thor Expedition has "/ 7 1904 St. 183 6i°30 L. N. i7°o8 h. W. Yt. 1800 M. Wire 

 gathered 3 young females, 11 adult males and 9 young males. 



The Monaco Expedition has taken immature females at two stations, and Far ran has recorded 

 adult males as well as immature ones from the west coast of Ireland "on four stations from depths of 

 600 to 1 1 50 fathoms". 



Remarks. I am pretty well convinced that the described species is identical with Sars' Gaidius 

 notacanthus, in spite of a few differences from the somewhat meagre description, viz: in the antennulae, 

 which are not "presque aussi longues que le corps". The male is probably identical with that described 

 by Far ran. The male, which Scott has referred to this species, is 5-9 mm. long and has rounded 

 lateral corners; accordingly it is not the male of Ch. notacantha, and it may more naturally be regarded 

 as the male of Ch. pustulifera. Sars and Farran as well as the other authors have provisionally 

 referred this species to Gaidius, as the adult females are not yet known. Several structural features 

 have, however, convinced me that this species like Ch. parvispina, and probably also Gaidius validus 

 Farran (1908, p. 32), G. cryptospinus G. O. Sars (1905, p. 10), divaricatus G. O. Sars (p. 10) and G. maximus 

 Wolf. (1906, p. 2), is nearly related to Undeuchcete spectabilis G. O. Sars (1900) p. 59 as well as to Chi- 

 rudina Streetsii, pustulifera and abyssalis. It differs from Gaidms temiispimis etc. by the three-seg- 

 mented exopodite of the first pair of legs with well developed Se Re I, by the wanting setae along 

 the inner margin of the second basipodite in the fourth pair of legs in the young specimens of the 

 fifth stage, as well as by the structure of the oral surface of the labrum and the lamina labialis. 



All the described males referred to this genus show a marked similarity to Undeuchcete in the 

 structure of the fifth pair of legs, and are accordingly different from those of Gaidius and Gaetanus. 



44. Chirudina parvispina Farran. 

 (PI. V figs 8 a; text-figs 42 a-g and 43 a-h.) 



1900? Undeuchsete spectabilis n. sp. G. O. Sars, pp. 59—63, pis XV — XVI. 

 1908. Gaidius parvispinus 11. sp. Farran, pp. 34— 35, pi. II figs 4—8. 



Description. Y'jjf (St. V). Size of young male from Thor St. 183 was 5-1 mm. ; anterior division 

 4-14 mm.; urosome 0-96 mm. Young female measured 442 mm. Farran's specimens measured 4-9 mm. 



