1012 THE VOYAGE OF H.M.S. CHALLENGER. 



examined, one of them a female, and the same thing is noticed by Mr. Chilton in his 

 account of Mcera spinosa, Haswell); the simpler form of palm regularly denticulate, 

 and fx-ino-ed with spine-teeth and setules, the other palm in the female specimen having 

 a straight portion near the hinge, then a gap, and the remainder sinuous ; the other 

 specimen had two gaps in the palm margin, not very wide apart ; the armature is the 

 same in all forms ; the finger is strong, gently curved or more strongly hooked, but 

 always closing down into the cavity between the apical tooth of the hind margin and the 

 palm border. 



First Perseopods. — Side-plates and branchial vesicles similar to those of the preceding 

 segment. The first joint extending far beyond the side-plate, with long setae on the 

 front margin above and spinules below, many long setse on the upper half of the hind 

 margin and spines on the lower half; the second joint with an apical spine behind ; the 

 third joint longer than the fourth or fifth, scarcely decurrent, with spines at four j)oints 

 on each margin ; the fourth joint longer than the fifth, with groups of spines at six 

 points of the serrate hind margin, and spinules at three points in front ; the fifth joint 

 with five groups of spines on the serrate hind margin, spinules at two points in front, and 

 an apical group of spines ; the finger short and stout, about half the length of the fifth 

 joint, with a dorsal cilium near the base, and one or two setules at the angle of the inner 

 margin in front of the nail, and a cilium near the outer margin. 



Second Perseopods. — Side-plates a little broader at the base than the preceding pair, 

 but otherwise similar. The first, third, and fourth joints of the limb shorter than in the 

 first perseopods, to which these are in other respects similar. 



Third Perseopods. — Side-plates with the front lobes as deep as the preceding side- 

 plates, spinules on the lower margin, the hind part shallow and scarcely lobed. The 

 brand) ial vesicles oval. The first joint long, about twice as long as broad, the margins 

 nearly parallel throughout, the front with spines, the hinder serrate but not deeply ; the 

 second joint with an apical group of spines in front, the third, fourth, and fifth joints 

 subequal in length, the third with apical groups of spines before and behind, setules on 

 the front margin, spines at three points of the hinder, the fourth with five groups of 

 spines in front and four behind ; the fifth widens a little distally, and carries four groups 

 of spines in front, and three behind ; the finger is larger than in the preceding pair. 



Fourth Perseopods. — Side-plates similar to the preceding pair but rather smaller, and 

 with the front lobe much narrowed. The limb very similar to that of the third perseo- 

 pods but much larger, and the armature much stronger, many of the spines, especially 

 those at the apex of the fourth and along the hind margin of the fifth joint, being of very 

 striking length ; the fifth joint is rather longer than the third or fourth, but this appears 

 to be sometimes the case also in the third perseopods. 



Fifth Perseopods similar to the fourth pair, but with the first joint and the third 

 smaller. 



