1556 THE VOYAGE OF H.M.S. CHALLENGEK. 



Third Perseopods. — Side-plates with the inner process produced acutely backwards. 

 The first joint of the limb long oval, narrowest distally, the slightly serrate froDt 

 margin being a little concave near the apex, which is produced a little below that of 

 the hind margin. 



Fourth Perieopods. — The first joint longer and much broader than that of the 

 third perseopods, the greatest breadth above the middle, below which the joint narrows 

 rapidly ; the front margin nearly straight, shallowly serrate and carrying little spines, 

 the squared apical lobe reaching considerably below the second joint; the hinder margin, 

 of which the upper part only is strongly convex, has a rounded apex not reaching to 

 the end of the second joint ; the third joint is not longer than the fifth, each of them 

 longer than the fourth, all the three being pectinate in the usual way along the front 

 margin and round the apex. 



Fifth Perseopods. — The side-plates with little semicircular marks, the lower hind 

 corner a little outdrawn. The limb nearly as in Brachyscelus crusculum. 



Pleopods. — The dilated arm of the cleft spine the longer; the rami long, joints 

 of the inner ramus thirteen or fourteen in number, of the outer fourteen or fifteen. 



Uropods. — Peduncles of the first pair about ecpial in length to the inner ramus, 

 reaching to the base of the telson ; the rami not very broad, carinate beneath, the 

 inner a little longer than the outer, as long as the telson, closely pectinate on the outer 

 margin, loosely serrate on the inner ; the peduncles of the second pair reaching 

 nearly as far as those of the first pair, the rami damaged ; peduncles of the third pair 

 short, the outer ramus slightly carinate, its outer margin smooth and almost straight, the 

 inner margin very convex, with the lower part pectinate ; the inner ramus missing. 



Telson triangular, much longer than the breadth at the base, constricted a little 

 near the acute apex, the sides having very little convexity. 



Length, about two-fifths of an inch. 



Locality. — August or September 1875, Pacific Ocean; surface. One specimen, female. 



Remarks. — The specific name refers to the sharply narrowed tip of the telson, 

 which is a distinguishing feature of the species ; the shape of the first joint of the 

 fourth peraeopods is another well-marked character. 



Brachyscelus mediterranea (Claus). 



1887. Tliamyris mediterranea, Claus, Die Platysceliden, p. 60, Taf. xvi. figs. 11-18. 



The segments a little imbricated. 



First Gnathopods. — The first joint almost straight, the wrist with five teeth on 

 the hind margin, four on the inner margin of the process, and the apical tooth, the hand 

 not reaching beyond the apical tooth of the wrist, having six teeth on the hind margin. 



