128 MESSES. NORMAN AND STEBBING ON THE 



The forked spines which are found on the hand of the last peraeopods in this species 

 are of unusual character. Somewhat similar cleft spines occur on the wrist and hand 

 of second gnathopods of A. elongata ; but in the latter case the two divisions of the 

 forked spines are both directed upwards, while in the former the chief prong is erect ; 

 the branch is strongly divergent. 



Genus 4. Hyssura. 



Hyssura producta, n. sp. (Plate XXV. fig. v.) 



General form very narrow and linear. Head rather outspread, flattened, shorter and 

 somewhat wider than first peraeon-segment ; following segments slightly but gradually 

 increasing in length to the fourth segment of the peraeon, which is of about the same 

 length as each of the two following ; last segment two thirds the length of the penulti- 

 mate. Pleon (fig. v. pi.), exclusive of telson, as long as the penultimate segment of 

 the peraeon ; telson more than half that length. Pleon consisting of six distinct 

 segments and a telson ; first five segments furnished with a pair of pleopods fitted for 

 swimming, sixth carrying two-branched uropods. 



Upper antennae with basal joint scarcely longer than broad, second and third sub- 

 equal to each other, and rather shorter than first ; flagellum three-jointed, not quite 

 so long as the two last of peduncle. Lower antenna? (fig. v. c), as seen from above, 

 closely approximated, their general appearance being very much those of A. elongata, 

 bent outwards from the fourth joint, which is the longest ; fifth half the length of 

 fourth ; flagellum of six articulations. 



First gnathopods (fig. v. gn 1 ) having basos and ischium strongly formed and of nearly 

 the same length ; meros short, produced on the back, and there forming a small simple 

 cup with rounded base for the reception of the base of the hand ; carpus minute, 

 triangular, with a produced point, which carries a single seta projecting forwards over 

 the base of the palm of the hand : hand twice as long as the united length of meros 

 and carpus, and equal in length to the basal joint of the limb, resting on the carpus 

 and fitting into the cup of the meros ; it tapers gradually, the palm not defined, crenated, 

 and bearing three or four spines ; finger much curved, and rather shorter than that 

 portion of the hand which projects beyond the carpus. 



Second gnathopods and first peraeopods, if anything, larger than the first, and of 

 nearly similar form ; but the carpus is more produced below, the lobe projecting over 

 the palm being larger, and the palm of the hand is more strongly crenated than the 

 first pair, the notches alternating with slender forked spines. 



Third and fourth peraeopods (fig. v. prp^) with the basos and ischium narrow ; meros 

 and carpus shorter and subequal to each other in length ; the limb is greatly constricted 

 at the junction of ischium and meros ; meros very narrow at first, and widening distally ; 



