1574 THE VOYAGE OF H.M.S. CHALLENGER. 



Second Gnathopods very like the first, but the first joint longer and rather more 

 slender, and the wrist widening distally, with straight or slightly concave distal margin 

 formino- the widest part of the joint and projecting much behind the hand, the hind 

 mar°in furnished with five setules or spinules successively larger, and three submarginal 

 hairs or setules, besides a little excessively fine furring. 



First Perasopods. — The first joint narrowest at the neck, the front margin straight ; 

 the second joint longer than broad ; the third joint subequal in length to the fourth, 

 which is a little narrower and slightly curved ; the fifth joint longer and narrower than 

 the fourth, slightly curved, the concave hind margin of this and the preceding joint 

 faintly furred ; the finger bulbous at the base, very slightly curved, less than half the 

 length of the fifth joint. There are microscopic setules on various parts of the 

 limb. 



Second Perasopods like the first, except that they are slightly stouter, and the third, 

 fourth, and fifth joints are longer. 



Third Perasopods much longer than the preceding pairs, the first joint not widely 

 expanded, more than twice as long as broad, with some small spines along the upper part 

 of the front margin which below is weakly serrate ; the second joint longer than broad ; 

 the third and two following joints much more elongate than in the preceding pair, the 

 third rather longer than the fourth ; the fifth slender, curved, much longer than either of 

 the two preceding joints, nearly as long as the first; the finger small, about a sixth of the 

 length of the preceding joint. 



Fourth Perasopods shorter than the third, the first joint rather longer and at the 

 upper part much more widely expanded, the front margin produced a little below the 

 hinder, and having a few spines, the convex hind margin smooth ; the second and third 

 joints rather larger than in the preceding pair, the third joint having its distal 

 margin finely pectinate and armed on either side with a couple of spines ; the fourth 

 joint about half the length of the third, the distal armature similar, but the pectination 

 much stronger, the front margin very minutely pectinate at the middle, but at a little 

 distance from the apex carrying four short broad teeth ; the fifth joint longer than the 

 third, curved, the concave front margin strongly pectinate ; the finger small. 



Fifth Perseo-pods. — The first joint narrowly pear-shaped, not so long as the first 

 joint of the third pair, but as broad at its broadest part ; the second joint not longer 

 than broad ; the third about twice as long as the second ; the fourth nearly twice as 

 long as the third, but narrower ; the fifth nearly as long as the fourth ; the minute finger 

 projecting in front of the fifth joint and strongly bent, so that the linear or setiform 

 termination is brought very near to the base and projects in advance of it. 



Pleopods. — Coupling spines minute ; cleft spine having the arm with the subapical 

 dilatation considerably longer than the other ; the first joint of the inner ramus 

 carrying five setae below the cleft spine ; the first joint of the outer ramus longer than 



