REPORT ON THE AMPHIPODA. 1401 



extreme length, narrowing distally, but with the distal margin still broad, convex in the 

 centre ; the inner plate small, not projecting beyond the base of the outer plates, the 

 latter not very much shorter than the joint to which they are attached ; on the straight, 

 sparingly serrate inner margin there are half a dozen spinules, there is one spinule 

 at the apex, and one in a little notch of the outer margin just below it. 



The Triturating Organs appear to have a feeble armature. 



First Gnathopods. — The first joint as long as the third, fourth, and fifth together, 

 expanded, the front margin convex, channelled along the lower half as in the following 

 limbs, having the gland-cells conspicuous and numerous ; the second joint about as 

 long as broad ; the third joint with a short front margin and a long straight smooth 

 hind margin, having two spines upon and two within the produced apex ; the trunk of 

 the wrist nearly as long as the hand, the produced hinder part not quite so long as the 

 hand, having the hinder margin and adjacent surface finely furred and carrying some 

 minute spinules at intervals, the apex acute, the front or inner margin divided into 

 about twenty-four teeth, near which there are four or five setules ; the long narrow hand 

 has two or three setules on the slightly convex front margin, the hinder margin being 

 divided into about twenty-eight teeth, near to which there are a few setules ; the 

 narrow apical border is, like that of the trunk of the wrist, microscopically pectinate ; the 

 finger is small, curved, having the inner margin just below the base pectinate with half a 

 dozen little teeth. 



Second Gnathop>ods very similar to the first. Branchial vesicles of great size, much 

 broader than the first joint. The first joint longer but scarcely broader than in the 

 preceding pair, the third joint rather shorter, the hand rather longer ; the inner margin 

 of the process of the wrist has twenty-eight teeth, the margin of the hand facing it has 

 thhly-four ; there is a minute setule at the tip of the finger. In these gnathopods, and 

 apparently in the first also, the finger can be retracted into the hand for almost its whole 

 length, if not for the whole length (see the enlargement of fig. gn. 2). 



First Perseopods. — Branchial vesicles like the following pairs very large. The first 

 joint longer than in the second gnathopods but less wide, the front margin convex, the 

 hinder nearly straight ; the second joint longer than broad, wider below than above ; the 

 third joint rather long and almost smooth-edged ; the fourth joint longer than the third, 

 with the hinder edge finely pectinate, produced into a little point, the distal margin also 

 finely pectinate, and this on the inner surface not lying parallel with the outer but 

 running obliquely up towards the hind margin ; the fifth joint slender, set on to the 

 front of the distal end of the preceding joint, which therefore projects behind it ; the 

 hind margin is finely pectinate. The apex of the fifth joint and the finger broken off. 



Second Perseopods. — The first joints like those of the first pair, but the pectination 

 of the fourth joint seemed to be slighter. The rest of the limb missing. 



Third Perseopods. — First joint not so long as in the preceding perseopods, a little 



(ZOOL. CHALL. EXP. PAET LXVII. — 1888.) X.XX 176 



