REPORT ON THE AMPHIPODA. 1305 



the fourth and fifth joints are to some extent three-sided, or may be said to have a 

 double hind margin ; the finger small, curved, acute, not a fifth of the length of the fifth 

 joint. 



Second Perseopods like .the first, but the joints a little longer, especially the fifth 

 joint. The branchial vesicles similar to the preceding pair, but much broader; the 

 marsupial plates much narrower than the preceding pair. 



Third Perseopods. — The side-plates like the preceding pair shallow, especially in 

 front, and broad. Branchial vesicles larger than the preceding pairs. The marsupial 

 plates similar to the preceding pair. The first joint narrower and longer than in the 

 second perseopods ; the third, fourth, and fifth joints also respectively a little longer than 

 those of the preceding pair, their front margins minutely spined, the hinder margin of the 

 third being also spined ; the fifth joint is straight, its hind margin smooth, nearly parallel 

 with the front tdl the apex, which is rounded, produced behind the insertion of the 

 finger, with oblique front margins, between which the minute, strongly curved, acute claw 

 can be exserted or retracted. ^ 



Fourth Perseopods. — Branchial vesicles with the oval outline interrupted below 

 the middle of the hind margin, a sort of suture marking off a narrow region from 

 the base as far down as this interruption, below which the vesicle is narrowed. The 

 first joint of the limb not longer than in the preceding pair, but broader, carrying 

 some small spines along the front margin; the second and third joints longer and 

 stouter than in the third perseopods ; the fourth joint nearly as long as the fourth and 

 fifth together in the preceding pair; the fifth joint narrower than the fourth, but 

 considerably longer, this and the three preceding joints unarmed ; the retractile finger 

 very little larger than that of the third perseopods, with several little unequal spines 

 on the upper part of the front margin, not decurrent. 



Fifth Perseopods not half as long as the fourth. The side-plates small, narrower 

 behind than in front. The first joint narrowing a little distally, its front margin carrying 

 some small spines, the convex hinder margins nearly smooth ; the third joint a little 

 longer than the fourth, the two together scarcely as long as the first; the fifth joint 

 longer than the third ; the retractile finger smaller than in the two preceding pairs, 

 with small spines or teeth on the inner margin directed slightly upwards. 



The relative proportions of the perseopods may be represented by the numbers 40, 

 44, 48, 66, 36. 



Pleopods. — Peduncles stout ; coupling spines short and small, each with four or five 

 retroverted teeth 'on either side ; the cleft spine stout, strongly feathered, the acute arm 

 longer than the other, denticulate on two edges ; the long first joint of the inner ramus 

 has five feathered setse below the cleft spine ; there are fifteen joints in this ramus and 

 nineteen in the outer. 



Uropods. — Peduncles and rami all more or less prismatic or three-sided in transverse 



(ZOOL. CHALL. ESP. — PART LXVII. 1888.) X.XX 164 



