266 Annals of the South African Museum. 



ISCHYROCERTJS CARINATUS 11. Sp. 



(Plate XXVIII. Fig. 18.) 



Body only faintly iridescent. Lateral lobes of the head obtuse, 

 eyes small, oval. Peraeou in adult <$ covered with rather long scattered 

 setae, segment 1 longer than 2, segments 1, 2, 6 and 7 each with a 

 high medio-dorsal keel extending on segments 1 and 2 the whole 

 length, on segments 6 and 7 only on the posterior part (of the seg- 

 ment), its upper margin straight and the angles rounded; in young 

 ^ J 1 measuring 2'5 mm. the peraeou is non-setose (except on the side- 

 plates) and without keels, those of 3 mm. are faintly setose, with a low 

 keel on 1st peraeon segment only ; the nonovigerous ? is nun- setose 

 and keelless. Side-plate 1 somewhat narrowed below, 4 largest, anterior 

 lobe of 5 as deep as 4, all side-plates sparsely setose on inferior margin 

 and with their outer surface covered with minute widely spaced granules 

 each bearing one or two wavy setules. Pleon keelless, postero-inferior 

 angle of 3rd segment rounded. 



Telson broader than long, apically obtuse, side-margins very slightly 

 concave, 2 submediau spines on upper margin near apex. 



First antenna, 1st joint shortest, 2nd and 3rd subequal, flagellum a 

 trifle longer than 3rd joint, 4-5-jointed, accessory flagellum 2-joiuted, 

 half as long as 1st flagellar joint, 2nd joint minute. 



Second antenna, ultimate peduncular joint a trifle longer tha'n 

 penultimate, flagellum equal to ultimate joint, 5- jointed. 



Mouth-parts, as in /. anguipes, but 1st joint of mandibular palp 

 shorter and 2nd more ..angular on inner margin. 



First gnathopod in $ , 2nd joint flask-shaped, very narrow at base, 

 swelling rapidly, the anterior apex forming a rounded lobe, 4th longer 

 than 3rd, its inferior margin straight or concave, 5th equal to 4th, 6th 

 equal to 4th and 5th together, oval, interior margin setose and with 

 4-5 spines in middle, the palm undefined from hind margin except by 

 its minute deuticulation. 



Second gnathopod in $ , 2nd joint very long, remarkably slender 

 proximally, strongly curved, the proximal ^ convex and serrate in 

 front, the distal f concave in front, distal anterior lobe serrate and 

 spinulose, 3rd with whole anterior margin produced as a rectangular 

 lobe, highest proximally, the ends rounded, 4th triangular, distal apex 

 rounded, with a small tuft of setae, 5th very short but as broad as 

 base of 6th, anterior apex subacute, inferior margin straight, minutely 

 denticulate, with a submarginal tuft of setae, 6th narrow-ovate, twice 

 as long as broad, palm and hind margin confluent, convex, with a step- 

 like constriction in middle, the distal half narrower than proximal, 



