OOPEPODA. 15 



Metridia gerlachei. 

 Metridia gerlachei, Giesbrecht, ' Belgica ' Report, p. 27. 



? 3 • 5-3 • 8 mm., very variable in size, occasionally a little larger and often smaller, 

 but the average of size of examples in the ' Discovery ' and ' Gauss ' collections is 

 rather less than that given by Giesbrecht for the ' Belgica ' specimens. The cephalo- 

 thorax is one and a half times as long as the abdomen, head separate from first thoracic 

 segment, last segment with rounded margins. The abdomen has the proportional 

 length of its three segments as 9 (genital) : 6 : 4 (anal), and the furca is one-fifth longer 

 than the anal, and three times as long as broad. It is divided into two portions by the 

 outer marginal bristle, of which the proximal is twice the length of the distal. 



The shape of the head and thorax is in this species characteristic, the back being 

 extremely gibbous, and the head with very bold curve, which makes it easily recognis- 

 able at sight from any other species of this genus. The anterior antennae are com- 

 paratively short and do not reach beyond the genital openings. The first and second 

 segments are coalesced ; the eighth, ninth, tenth, eleventh, have only faint indications 

 of separation ; the thirteenth and fourteenth joints are not so clearly divided as the 

 others. There are strong teeth on one, two, three, five, seven (one each), those of 

 the third, fifth, seventh joints the strongest, and directed straight forwards. The 

 sesthetasks are numerous. 



The endopodites of the second pair of feet have the usual excavation and hook 

 process on the first segment, but in this species the inner hook is exceedingly strong. 

 In the fourth pair the end saw is only two-fifths of the whole length of the Re 3 

 (shorter than in Giesbrecht's examples). 



The fifth pair consists on each side of three segments, but the distal segment is 

 more or less completely divided into two, the division however is not complete. The 

 two basal joints are of about the same length and breadth, each as broad as a little 

 over half the length. The third joint, however, is not more than four-fifths as long as 

 the basals, and only half the breadth. The second joint bears one short distal bristle, 

 the last joint one outer marginal bristle in the proximal half, and three distal bristles, 



of which the innermost is the longest and thickest, the outermost the shortest. 



'i 



Metridia princeps. 

 (Plate III., figs. 3, 4, 5.) 



Metridia princeps, Giesbreclit, Atti Line. Rend., Ser. 4, v. 5, p. 24. 



Fauna u. Fl. Neap. XIX., p. 340. 



Farran, Ann. Rep. Fish. Ireland 1902-03, PL II. App. II. (1905). 

 ? Metridia macrura, Sars, Bull, du Mus. Oceanog. Monaco, 1905, no. 40, p. 7. 



Though only one example of this species occurred in the ' Discovery ' collection, it 

 was frequent in the ' Gauss ' collection, not only at several Atlantic stations, but also 



