REPORT ON THE AMPHIPODA. 1561 



Third PersBOpods. — Side-plates bilobed, much broader -than deep, the front lobe 

 rather deeper and much broader than the hind one. Branchial vesicles similar to the 

 preceding pairs, but larger, broader above than below. Marsupial plates scarcely 

 so large as the preceding pair. First joint oval, with the narrower end at the base, 

 the front margin very regularly convex, scarcely serrate, fringed with spinules ; the 

 hind margin with the convexity most developed at the lower end, smooth ; second 

 joint short, with spinules on the front margin ; third joint rather longer than the 

 fourth, scarcely shorter than the fifth, all three resembling the corresponding joints 

 in the two preceding pairs, but slightly exceeding them in length ; the finger also is 

 similar. 



Fourth Perteopods. — Side-plates less broad than the preceding pair, the front lobe 

 much deeper than the hind one, and with a straight front margin. The branchial vesicles 

 not quite so large as the preceding pair, much widened at the upper hind corner. The 

 limb differing very little from that of the third perseopods, the hind margin of the first 

 joint more regularly convex, the third joint a little longer, the fifth perhaps scarcely so 

 long, and a little widened at the upper part so that its front margin is not concave, the 

 fourth and fifth joints having their front margins minutely pectinate ; the finger a little 

 longer and straighter than in the preceding pair. 



Fifth Perteopods. — Side-plates not bilobed, very little broader than deep. First joint 

 as broad as in either of the two preceding pairs but not so long, suddenly narrowed 

 distally, the front margin very slightly, the hinder for the most part very strongly, con- 

 vex ; at the distal end the hind margin is concave and channelled ; the remaining joints 

 together do not quite equal the length of the first, and but little exceed its breadth ; 

 the second joint short, with some spinules in front, the third joint longer than the second, 

 a little shorter than the fourth, which has a convex front margin ; the fifth is very little 

 shorter than the fourth, with a convex hind margin, the front concave for the lower two- 

 thirds ; the finger, which is scarcely discernible except with a high power, has some- 

 thing of a horse-shoe shape, the lower point projecting forwards a little in advance 

 of the upper. 



Pleopods. — The two coupling spines have short slender shafts, the apical dome or cap 

 having its rim cut into several teeth ; the cleft spine is attached close to the top of the 

 first joint of the inner ramus, the subapically dilated arm about as long as the other, 

 the dilatation small ; below it on the first joint there are four plumose setae ; the first 

 joint of the outer ramus has a tongue-like interlocking process ; the joints, of this ramus 

 are eleven in number, those of the inner ramus ten. 



Uropods. — The peduncles of the first pair reach beyond those of the second ; they are 

 a little shorter than the rami ; the outer ramus is scarcely so long as the inner ; they are 

 both lanceolate, carinate beneath, with finely pectinate margins, and reach beyond 

 the other pairs ; the peduncles of the second pair are shorter than the rami, and only 



(ZOOL. CHALL. EXP. PART LXVII. — 1888.) Xxx 196 



