888 THE VOYAGE OF H.M.S. CHALLENGEE. 



the same length as in the first gnathopods or a little longer, thinner, similarly armed, but 

 with the palmar spines spread over rather more space ; the finger similar ; the wrist in 

 this remarkable limb is three times as long as the elongate hand. 



First Perwopods. — Side-plates forming below a triangular channelled and carinate 

 serrate-edged process as in the preceding pairs, but also throwing out from the centre of the 

 upper part a similar process which takes a backward curve. The branchial vesicles and 

 marsupial plates similar to those of the preceding pair, but rather larger. The first joint 

 reaching beyond the side-plate, very slightly produced and furnished with spinules on 

 the hinder apex ; the second joint produced and furnished in like manner, and with one 

 or two spinules on the hind margin on the inner surface, each of these joints having a 

 small semicircular lobe on the distal margin ; the third joint, which is nearly as long as 

 the first, is distally a little expanded and a little produced in front ; it has three or four 

 spinules on the rather irregular margins both in front and behind ; the fourth joint, which is 

 considerably shorter, has four spinules on the front margin, and short spines at six points 

 of the hind margin ; the fifth joint longer than the fourth but shorter than the third, has 

 seven or eight spinules in front, spinules at eight points behind, the distal margin slightly 

 lobed on the inner surface ; the finger is short and broad except at the curved tip, and 

 at intervals along the inner edge carries some eight spinules ; there is a cilium at the base 

 of the nail, and some cilia apparently along the hind margin. 



Second Peneopods closely resembling the first ; the side-plates throwing out an angle 

 behind to assist in interlocking it with the following side-plate. 



Third, Fourth, and Fifth Perseopods.- — The side-plates of these three pairs are much 

 alike, the basal part or body of the plate successively smaller, the back-turned serrate 

 process successively longer ; when examined from below there is seen to be a flat process 

 or lobe to the rear of the great process, the lower angle of which is turned forwards. 

 The limbs are similarly formed, the fourth rather longer than the third, the fifth than 

 the fourth. The first joint is so much channelled that it presents four longitudinal 

 carinas or ridges, its lower hinder margin on the outer surface is produced in a 

 rounded lobe which completely overlaps the short second joint, which like the three 

 following joints is carinate in front ; the third joint is decurrent behind with a long 

 pointed process, and has some spinules along the front margin ; the fourth joint is rather 

 shorter, similarly decurrent, with spines on the front margin ; the fifth joint has the hind 

 margin longer than the front, but without an elongated apex ; the front margin has 

 several small spines ; the finger is similar to that of the first perasopods. 



Pleopods. — The coupling spines very small, with two lateral teeth and an apical one ; 

 the cleft spines slender, five in number, at least on one of the pleopods ; the joints of the 

 rami from twenty to twenty-three in number. 



Uropods. — The peduncles channelled above, all reaching back nearly to the same 

 point, the first pair a little beyond the second, and the second beyond the third, and the 



