40 EEV. T. E. E. STEBBING— BISCATAN PLANKTON : 



The uropods are of special interest. After discussing the variations in the third 

 peraeopods, Dr. Bovalliiis observes, " In the form and serration of the iiropoda there 

 is a similar variation, but more connected with the age of the animal, so that the 

 older animals which have attained a length of 10 or 12 mm. have the uropoda 

 comparatively much broader than in the young, less distinctly serrated, and hardly 

 emarginated at the apex, while the young have the first and second pairs very narrow, 

 sharp-pointed, and finely serrated, and the third pair only a little dilated, sharp-pointed, 

 and deeply emarginate." 



In the specimen here described, which is a very little shorter than the smallest of 

 those examined by Bovallius, a completely new relation comes into view. All the 

 uropods are, as Bovallius says, and as the figure (text-fig. 2, p. 39) depicts, sharp-pointed, 

 but there is no perceptible serration and no emargination. The first pair is slightly the 

 longest, though not reaching so far back as the third. The second is considerably shorter 

 and slightly narrower than the other two, and has some way above the middle of the outer 

 margin a minute spinule. The third pair have a slender spine-like outer ramus, proved 

 to be a ramus and not a spine by the muscles attached to it. Tlie j)]ace of insertion of 

 this ramus shows that the peduncular jJart of the uropod is slightly longer than the 

 completely coalesced inner ramus, which is much broader than the outer but not fully 

 twice as long. In the adult there appears to be no reminiscence of this outer ramus, 

 unless the almost terminal emargination of the broad plate into which the uropod 

 eventually develops indicates the place of insertion. Anyone observing the uropods 

 and telson of this young Primno on the hinder part of the pleon detached from the rest of 

 its body might well be excused for determining them as belonging to one of the 

 Scinidse. 



Occurrences : 25 e. 50 to fathoms. 1 specimen, about 1"4 mm. lone 



31 b. „ ,, „ 1 ,, 2"5 mm. long. 

 32 /i. ,, „ ,, 1 „ 3 mm. long. 



32 m. 75 to fathoms. 1 „ young. 

 30 h. 100 to fathoms. 1 „ 3 mm. long. 



Fam. T Y p H I D ^. 



Beachtsceltjs, Bate, 1861. 



1861. Brachyscelus, Bate, Ann. & Mag. Nat. Hist. ser. 3, vol. viii. p. 7. 



1888. Brachyscelus, Stebbing, 'Challenger' Amphipoda, Reports, vol. xxix. p. 1543. 



22. Brachyscelus meditekranetjs (Claus), 1887. 



1887. Thamyris mediterranea, Claus, Die Platysceliden, p. 60, pi. 16. figs. 11-18. 



1888. Brachyscelus mediterranea, Stebbing, ' Challenger ' Amphipoda, Reports, vol. xxix. p. 1556. 

 1900. Brachyscelus mediterranevs, Chevreux, Ampliipodes de I'Hirondelle, p. 154. 



1900. Brachyscelus crustulum, Norman, Ann. & Mag. Nat. Hist. ser. 7, vol. v. p. 134. 



1903. Brachyscelus mediterraneus, A. O. Walker, Ann. & Mag. Nat. Hist. ser. 7, vol. xii. p. 231. 



A single specimen, 45 mm. long, agrees well with the figure assigned by Claus to 



D* 



