REPORT ON THE AMPHIPOPA. 1033 



Fourth Per&opods. — Side-plates narrow. Branchial vesicles smaller than the first 

 joint, in position pointed backwards. First joint similar to that in the preceding pair, 

 but larger, rather more widened at the top, with spines at nine points of the front 

 margin ; the two following joints also like those of the preceding pair, but larger, with 

 stronger spines, and the third joint proportionately a little more decurrent both in front 

 and behind. 



Fifth Perseopods. — Side-plates small. The first joint larger than in the preceding pair, 

 broader at the centre ; the two following joints similar to those of the preceding pair, 

 not larger. 



Pleopods. — Coupling spines broad at the base, with from two to three pairs of 

 retroverted teeth below the apex ; in the third pair there is a strong spine at the inner 

 apex of the peduncle close to the coupling spines, and many times as long, and another 

 spine about half its length at the outer apex ; cleft spines four in number in the first two 

 pairs, three in the third pair, the arms nearly equal in length ; the joints were nine to 

 the inner, ten to the outer, ramus of the third pair. 



Uropods. — Peduncles of the first pair a little longer than the rami, with several 

 spines along the margins, and some large and strong ones about the apex, the outer 

 ramus a little shorter than the inner, each with a few spines on the margin, and a strong 

 apical group ; the peduncles of the second pair a little shorter than the rami ; the rami 

 respectively shorter than those of the first pair, but, as well as the peduncles, very 

 similarly armed ; the inner margin of the inner ramus more closely spined ; third 

 uropods missing. 



Telson small, scarcely longer than broad, cleft nearly to the base. The dehiscence 

 boat-shaped, bounded by a sharp apex on either side, while the slightly converging outer 

 lateral margins form two other apices still more produced, each pair of apices having the 

 interval between the two points occupied by two long unequal spines, which extend back 

 much beyond the apices themselves. 



Length. — The specimen, in the position figured, measured, from the front of the head 

 to the back of the third pleon-segment, a quarter of an inch. 



Locality.— Station 186, between Cape York and the Arrou Islands, September 8, 

 1874; lat. 10° 30' S., long. 142° 18' E. ; depth, 8 fathoms; bottom, coral mud. 

 One specimen. 



Remarks. — Dana's Gammarus siduensis was taken in the " Sooloo Sea ; from a small 

 island off the harbour of Soung ; among seaweed floating off the shore." He states that 

 " the stylets [uropods] are all long, and extend equally far backwards." 



(ZOOL. CfiALL. EXP. — PART LXVII. — 1887.) ^ xx 130 



