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



uncovered, broader above than below, the front margin concave, the lower part of the 

 plate squared, with rounded angles. First joint of the limb extending much beyond 

 the side-plate, narrowest near the base, then expanding to its greatest width and 

 narrowing slightly to the end ; second joint as long as the third, with some long setses 

 chiefly at the hinder distal end ; the third joint distally rounded, its whole hinder margin 

 densely clothed with long setse ; the wrist triangular, cup-shaped, scarcely longer than 

 the preceding joint, broad distally, the free hind margin setose ; the hand rather 

 broader than the wrist and much longer, of equal width throughout, bearded on the 

 hinder margin with seta3, which become shorter in proximity to the palm ; the front 

 margin with only a distal tuft ; the -palm at right angles to the hind margin, defined by 

 two spines socketed deeply in the surface of the hand ; a row of cilia on either side of 

 the palm margin ; the finger much curved, the tip of the nail fitting exactly to the end 

 of the palm. 



Second Gnathopods. — Side-plates oblong. Branchial vesicles elongate, the part that 

 rises above the neck rounded, the central part the widest, the end narrowing almost to a 

 point. The first joint of the limb extending beyond the side-plate, not so long as the 

 branchial vesicle, straight, only slightly expanded below ; second joint longer than third ; 

 third rounded below, minutely furred on the breast or hind margin, which also carries a 

 few spines or setae ; the wrist at first a little narrowed, then gradually widening a little, 

 longer than the hand, furred on the hind margin, carrying very few setse ; the hand oval, 

 minutely furred and covered with small scales, carrying on the hind margin four groups 

 of spines short but strongly pectinate on two edges, a larger group in several rows and 

 of varied sizes on and near the front apex over-arching the minute finger, which is set in 

 the middle of the apical margin and closes pretty tightly over the inward curving ciliated 

 palm. In the figure, as in the specimen, the hand and wrist of this delicate and not very 

 elongate limb are twisted round, and of the wrist it is not a lateral surface that is shown 

 but rather the reo;ion of the anterior margin. 



First Perseopods. — Side-plates similar to the preceding pair, rather broader. 

 Branchial vesicles long, of nearly uniform breadth except at the neck. First joint of the 

 limb scarcely reaching beyond the side-plate ; third joint longer than fourth or fifth, 

 scarcely decurrent, of almost uniform breadth, this and the other joints having setse on 

 the hinder margin ; fourth joint rather thicker, barely shorter, than the fifth ; fifth joint 

 with six sets of spines as well as set» on the hinder margin ; finger very short and 

 stumpy, inner margin furred like the preceding joints ; a minute nail, abruptly narrower, 

 set among cilia. 



Second Perieopods. — Side-plates broadly oblong, excavate behind, the hinder margin 

 forming a slightly outdrawn angle at the bottom of the excavation, lower margin ciliated ; 

 the joints of the limb in close agreement with those of the preceding pair. 



Third Perseopods. — Side-plates rather broader than deep, front lobe descending a 



