1412 THE VOYAGE OF H.M.S. CHALLENGEK. 



shorter ; this is fringed with spines along the margin facing the hand and at the apex, 

 which is not quite acute ; the hand is longer and straighter than in the first gnathopods, 

 with fewer surface spines and perhaps less pectination ; the finger is as in the preceding 

 pair, but not more than half the length of the hand. 



First Perseopods. — The first joint narrow above and widened below, with sinuous 

 slightly serrate front margin, the hinder convex, carrying a few little spines ; the second 

 joint with some small spines on the hind margin; the third joint not longer than the 

 second, but distally wider, with spines along the faintly pectinate hind margin ; the 

 fourth joint (or wrist) large, ovate, the front margin convex, smooth, with spines at the 

 apex, the inner surface carrying some spines, the hind margin finely pectinate and 

 fringed with numerous spines, this margin in large specimens being sinuous, since in 

 such specimens the apical part of the joint is narrowed almost abruptly; the fifth joint 

 as long as, or longer than, the fourth and folding against it, narrow, curved, with convex 

 front margin, the hind margin concave, pectinate ; the finger slender, smooth, curved 

 at the tip, not half the length of the fifth joint. 



Second Perseopods similar in general shape and armature to the first, but with all 

 the joints except the second larger, the first joint longer and of more uniform breadth, 

 the fourth much longer and broader, the fifth only a little longer, so that in this pair it 

 is shorter than the fourth joint. 



Tliird Perseopods. — The side-plates broad and shallow. The first joint channelled 

 behind, in front somewhat bowed out near the middle, with several spines along the 

 front margin, of which the upper part is smooth ; the second joint short, almost smooth; 

 the third joint widening distally, as long as the distal breadth, with some spines along 

 the front, and at the apex of the hind margin ; the fourth joint considerably longer than 

 the first, distally narrowed, with numerous spines along the serrate front margin, and 

 some also along the hind margin ; the fifth joint is much longer and narrower than the 

 fourth, with a bulbous base ; the front margin has a few spines, but is chiefly dis- 

 tinguished by the pectination, which near the base is faint, but grows stronger and 

 stronger as it approaches the apex ; the finger short and slender, a little curved. 



Fourth Perseopods much shorter than the third, the inequality depending on the 

 first, fourth, and fifth joints ; the first joint channelled behind, with spines along the 

 lower half of the sinuous front margin ; the second joint short ; the third as long as in 

 the preceding pair, similarly armed, much narrower ; fourth joint rather shorter than the 

 first, with spines along both margins, numerous on the faintly pectinate front, and 

 slender feathered spines along the inner surface ; the fifth joint slightly curved, narrower 

 than the fourth, rather longer than the first, with spines along the slightly convex and 

 serrate hind margin, others along the pectinate front margin, with slender spines on the 

 adjacent surface ; the finger slender, smooth, almost straight, not a quarter the length 

 of the fifth joint. 



