1554 THE VOYAGE OF H.M.S. CHALLENGES. 



the hind margin of the fifth joint and some extremely minute pectination of the distal 

 margin of the fourth. 



Third Perseopods. — Inner process of the side-plates with the lower corner produced 

 backwards, scarcely acute. The first joint shorter than the remaining joints together, 

 moderately expanded, narrowing downwards, the front margin straight except at the 

 two extremities, not apically produced, the hinder margin convex ; the second joint 

 reaching below the first ; the third very little longer than the fourth, the fifth longer 

 than the third, the finger not a third the length of the fifth, all these joints smooth. 



Fourth Perasopods. — The inner process of the side-plates with a very irregular lower 

 margin. The first joint not longer than the remaining joints together, sirmlar in shape 

 to the first joint of the third perasopods, but rather longer and much broader, the apex 

 of the front margin also being produced below that of the hinder margin as far as the apex 

 of the short second joint ; the third joint considerably longer than the fourth, pectinate 

 except near the base along the front margin, and much more finely on the distal margin; 

 the fourth joint similarly pectinate, but more strongly and irregularly on the distal 

 margin ; the fifth joint longer than the fourth, shorter than the third, pectinate on the 

 front and distal margins ; the finger about a third of the length of the fifth joint. 



Fifth Perseopods. — First joint pear-shaped, not very widely expanded, the front 

 margin much straighter than the hinder one ; the remaining joints together more than 

 two-thirds of the length of the first ; the second joint as broad as its length ; the third 

 not very much longer or broader than the fourth ; the fourth broader but not very much 

 longer than the fifth ; all of the joints smooth, the fifth produced in front into a small 

 triangular process, round which the small slender finger curves, a small setule projecting be- 

 tween. In ab 1 the species there is such a setule, and in some it is a little doubtful whether 

 the finger is really folded or only curved round a projecting apex of the fifth joint. 



Pleopods. — The rami rather short, with nine.joints to the inner, and ten to the outer 

 ramus. 



Uropods. — Peduncles of the first pair reaching rather beyond the base of the telson, 

 equal in length to the inner ramus, the distal margin of the under surface pectinate ; the 

 rami carinate beneath, the outer much narrower and a good deal shorter than the inner, 

 pectinate on both margins except at the widened part close to the base ; the inner ramus 

 reaching beyond the telson, pectinate on the outer margin, a little serrate on the lower 

 part of the inner ; peduncles of the second pair shorter than the inner ramus, the rami 

 damaged, seemingly very similar to those of the first pair but a little smaller and not 

 carinate ; peduncles of the third pair not longer than the distal breadth, the outer ramus 

 shorter and narrower than the inner, pectinate on the lower part of each margin ; the 

 inner ramus reaching beyond the telson, the outer margin pectinate on the lower half, 

 the inner margin almost straight and smooth, the apex broad but worn, so that the true 

 apex may be acute. 



