ENTOMOSTRACA OP THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 309 



the spine, which spring from near its distal end, while the inner margin of the same 

 joint and the outer margin of the inner ramus are both fringed with delicate hairs, as 

 shown in the drawing (h'g. 24). Another feature here is the presence of three small 

 teeth on the transverse end of the first joint of the outer ramus (see fig. 24).- 



The next three pairs are somewhat similar in structure to the same appendages in 

 Parathalestris jacksoni (T. Scott). 



The fifth pair are tolerably large and foliaceous ; the outer segment, which is broadly 

 ovate in form, is provided with six setae ; five of them spring from the distal half of the 

 outer margin and apex, and one from the lower part of the inner margin ; the upper- 

 most three on the outer margin are moderately stout and widely apart, while the two 

 at the apex are slender and close together. The inner portion of the basal joint is 

 shorter than the outer, and is somewhat triangular in outline, being broad at the 

 proximal end, and tapering from thence to the rounded extremity ; five setae spring from 

 the distal end of this inner segment ; the three on the inner aspect are moderately stout 

 and placed widely apart ; the other two spring from the lower half of the outer margin 

 and are close together ; they are smaller than the others (fig. 25). 



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

 60 43' 42" S., 44 38' 33" W. Only one or two specimens were observed. 



Remarks. The species now described is in its several appendages not unlike the 



northern form mentioned above, the fifth pair of thoracic legs being remarkably 



similar ; there are, however, a few differences of more or less importance between them 



the species referred to being, for example, distinctly larger, and the caudal rami 



entirely different. 



Genus Idomene, Philippi, 1843. 

 Idomene forficata, Philippi. (PI. III. figs. 1-6; PI. IV. fig. 1 ; PI. IX. fig. 29.) 



1S43, Idome.ne forficata, Philippi, Archivf. Naturyescliiclite, p. 65, pi. iii. fig. 4. 



1880, Dactylnpm flavus, Brady, Monogr. Brit. Copep., vol. ii. p. 116, pi. Ivi. figs. 1-11. 



1906, Idomene forficata, G. O. Sars, Crust, of Norway, vol. v. p. 134, pi. Ixxxii. 



Female. Body somewhat depressed, expanded in front, but becoming narrower 

 towards the distal end. Length, '57 mm. 



Antennules short and composed of seven joints ; the first four joints are tolerably 

 large, but the others are smaller, the penultimate joint being rather shorter than the 

 preceding one, and about half as long as the next. Antennae with the outer ramus 

 small and biarticulate. 



The second maxillipeds are of moderate size ; a stout seta springs from the end of 

 the first joint, while the second is armed with a long slender claw, and a small bristle 

 also springs from near the distal end of its inner margin. 



The four pairs of swimming feet have both rami three-jointed. The first pair are 

 stout, and the second basal joint is furnished with a stout seta on both the outer and 

 inner margins ; the first and second joints of the outer ramus are tolerably large, but 



(BOY. soc. EDIN. TRANS., VOL. XLVIII., 555.) 



