1909.] FROM THE BAY OF BISCAY. 863 



hollow at the angle between the two large sen.sory spines. In the 

 large female the palm is greatly elongated, the piojecting lobe 

 being one-fifth of the distance from the finger-articulation, with a 

 deep indentation immediately following it ; equidistant between this 

 lobe and the palmar angle is a slighter indentation with a small 

 projection following ; the whole of the margin crenate. The 

 palmar angle projects considerably beyond the palm-level, the tip 

 of the finger impinging against the under surface of the palm 

 some distance from the angle instead of meeting it, as in the 

 young animal. The palm is bordered on either side with the 

 sensory spines characteristic of this species, and with long cleft- 

 tipped setae, the under surface thickly setose. The finger is 

 strong, curved and serrate ; the serrations are very distinct in the 

 immature specimen, 4 in number with a setule inset in each, as 

 in the first gnathopod ; much less distinct in the young female, 

 6 in number ; and only visible in the large specimen under a high 

 power, when they show as oblique incisions. 



Male (fig, 13). — The hand in the young male is about twice as 

 long as broad, with the palm half as long again as the hind margin. 

 As in the female, transverse rows of sensory setas are deeply inset 

 along the hind margin, 5 in the female, 8 in the male. The 

 palmar angle is as in the young female, the tip of the finger 

 meeting it and fitting between the groups of sensory spines. 

 Walker describes the palm margin (p. 231) as "divided into three 

 lobes with crenate edges by two deep sinuses." The edges of 

 these lobes are of very delicate structure, pellucid, with the 

 sensory spines and setse inset considerably within the margin. 

 The finger is large, stout, with a deep indentation proximally on 

 the inner edge; it has 14 of the oblique incisions in the young 

 male. The larger male agrees with the one described, with the 

 accentuation of the lobes and sinuses natural to the gi'eater 

 development. 



Perceopods. — The 1st and 2nd perfeopods are practical)}^ sub- 

 equal in length ; basal joints with some of the long sette on either 

 side, as in the gnathopods. Hinder perasopods not difieiing 

 much in length, basal joints expanded, rounded oval, carrying 

 small spines on the anterior margins, and minute setules on the 

 posterior ; 4th joints produced downwards at the posterior angle 

 to long triangular lobes ; 5th joints also produced but in a less 

 degree. The female diflfers from the male in having the 4th joints 

 shorter than the 5th, instead of longer ; this difierence is very 

 slight in the first two perseopods, but marked in the hinder ones. 

 Another difierence lies in the terminal joints ; those of the female 

 being provided with two small teeth on the inner margin, while 

 those of the male have the margin entire (figs. 15, 16, and 17). All 

 the terminal joints carry a plumose hair on the outer curve. The 

 finger of the 3rd pei-seopod in the female difiers a little in form 

 from the others ; it is more hollowed underneath, and has the 

 second auxiliary tooth much produced. The sensory spines are 

 as in the gnathopods. 



