304 DR THOMAS SCOTT ON THE 



end joint of the outer ramus is about twice as long as the preceding joint. It is also 

 moderately narrow, and furnished with two rather stout marginal spines and two at 

 the apex, the inner apical spine being nearly as long as the joint to which it is 

 articulated (fig. 27). 



The fifth pair are somewhat like the same pair in Tisbe (jracilis ; the second joint, 

 however, differs in being rather wider in proportion to its length. The seta on its 

 inner margin is also articulated nearer the middle of the joint, and the whole of the 

 inner aspect of the joint is covered with minute hairs (fig. 28). 



Habitat. Scotia Bay, South Orkneys; collected in June 1903; Station 325, 

 60 43' 42" S., 44 38' 33" W. Rare. 



Remarks. This form resembles Idywa gracihs, and might be considered as only 

 a variety of that species, but the inner ramus of the first pair of swimming legs is 

 proportionally and distinctly more elongated, and the second joint of the fifth pair is 

 also more broadly ovate. Because of these differences and one or two others alluded 

 to in the description, the species ought, I think, to be considered distinct. 



Genus Psamathe, Philippi, 1840. 

 Psamathe longicauda, Philippi. (PI. V. figs. 16-22.) 



1840, I'samathe longicauda, Philippi, Archiv f. Naturgesch. (1840), p. 89, pi. iv. fig. 1. 

 1866, Scutdlidium tisboides, Glaus, Die Copepoden fauna von Nizza, \i. 21, pi. iv. figs. 8-15. 

 1880, Brady, Monogr. Brit. Gopep., vol. ii. p. 175, pi. Ixviii. figs. 1-10. 



1905, Psamathe longicauda, G. O. Sars, Crustacea of Nonvay, vol. v. p. 83, pi. xlix. 



A single specimen of this Harpactid was obtained in a plankton gathering collected 

 at Station 27 in 13 38' N., 25 09' W. 



The body in this species is considerably flattened, and there is a distinct break 

 between the anterior and the posterior portions, best seen when viewed from above, 

 the former being expanded, while the latter is narrow (see fig. 16). 



The antennules are composed of nine joints ; the first three are elongated and moder- 

 ately stout, and are together about twice the entire length of the remaining six joints : 

 the end joint is slender and rather longer than the three preceding joints combined 

 (%. 17). 



Antennae with the outer ramus four-jointed and not more than half the length of 

 the inner one ; it is also articulated to the outer distal angle of the second basal joint 

 (fig. 18). 



Maxillipeds moderately stout ; first pair smaller than the second and armed with 

 two claw-like terminal spines (fig. 19). Second maxillipeds robust; the basal joint is 

 provided with a stout plumose seta on its inner distal angle, and the end joint with 

 three stout terminal claws and a small plumose bristle (fig. 20). 



The first pair of thoracic legs are moderately stout, and both rami are composed of 

 three joints, but the end joints are extremely small and bear peculiar recurved terminal 



(ROY. soc. EDIN. TKANS., VOL. XLVIII., 550.) 



