AMPHIPODA. 27 



edges dentate ; spine row long, of about twenty spines ; the palp, which is set on in 

 front of the middle, is longer than the mandible ; the first joint about one- third as 

 long as the second, which is subequal to the third. One of the mandibles appears to 

 be without a secondary cutting plate. 



First maxillse: Inner plate with about 12 plumose setse on its inner margin. 



First gnathopods : First joint stout, rather longer than the side-plate, and subequal 

 to the wrist and hand united ; these are subequal to each other, the wrist rather the 

 wider ; the hand is oval, the palm undefined, pectinate ; the whole hind margin sparsely 

 and unequally spinous. Dactylus with 5 spines on the inner margin. 



Second gnathopods are like the first, except the palm, which is more transverse, and 

 about half as long as the rest of the hind margin. 



Second perseopods : Side-plates reaching below the second joint. First joint narrow, 

 oblong, subequal to the third and fourth united ; third rather longer than the fourth, 

 and shorter than the fifth. Dactylus continuous with the fifth joint, as long as the 

 third, and slightly curved. 



Third and fourth perseopods subequal : First joint oblong, twice as long as wide ; 

 third joint half as long as the first, acutely produced behind ; fourth joint subequal to, 

 and fifth rather longer than the first. Dactylus very long, about one-fifth longer 

 than the fifth joint, and tapering very gradually. These two pairs appear to be 

 generally carried elevated over the back. In the largest specimen (25 mm.) the 

 dactyli are not quite so long relatively. 



Fifth perseopods are considerably shorter, and the first joint wider, than the third 

 and fourth ; hind margin of the first joint convex, obscurely serrate, and produced 

 downwards in a rounded lobe almost to the middle of the third joint ; this is 

 much produced behind, and is a little shorter than the fourth, which is as long as the 

 dactylus and shorter than the fifth joint. 



First and second uropods ; The rami longer than the peduncles, the outer shorter 

 and narrower than the inner. 



Third uropods : Rami nearly twice as long as the peduncle, subequal, the outer 

 the narrower, with fine spines on both margins. 



Telson, reaching to about one-fourth the length of the rami of the third uropods, 

 deeply notched at the end, with a minute notch on the tip of each division. 



The above description, with the exception of that of the external characters of the 

 animal as seen without dissection, is taken from a young specimen 6 mm. long. 



FAM. IPHIMEDIIDtE, Stebbing. 



Iphimedia pacifica. 

 IpUmedia pacifica, Stebbing. 



W.Q., 20 Feb., 1902, 20 fm., one; 14 Jan., 1903, 130 fm., one, young, about 

 8 mm.; 14 July, 1903, 130 fm., one, length 24 mm.; 30 Sept., 1903, one, length 

 20 mm. ; two on 4 Sept., 1905, one, length 30 mm. 



