ho 
(or) 
fe) 
Annals of the South African Museum. 
IscHYROCERUS CARINATUS N. Sp. 
(Plate XXVIII. Fig. 18.) 
Body only faintly inidescent. Lateral lobes of the head obtuse, 
eyes small, oval. Peraeon in adult ¢ covered with rather long scattered 
setae, segment 1 longer than 2, segments 1, 2, 6 and 7 each witha 
high medio-dorsail 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 
3S g measuring 2°5 mm. the peraeon is non-setose (except on the side- 
plates) and without keels, those of 5 mm. are faintly setose, with a low 
keel on Ist peraeon segment only; the nonovigerous ? is non-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 submedian spines on upper margin near apex. 
First antenna, Ist joimt shortest, 2nd and 3rd subequal, flagellum a 
trifle longer than 5rd joint, 4—5-jointed, accessory flagellum 2-jointed, 
half as long as Ist flagellar joint, 2nd joint minute, 
Second antenna, ultimate peduncular joint a trifle longer than 
penultimate, flagellum equal to ultimate joint, 5-jointed. 
Mouth-parts as in I. anguipes, but Ist 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 38rd, 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 denticulation. 
Second gnathopod in ¢@, 2nd joint very long, remarkably slender 
proximally, strongly curved, the proximal 4 convex and serrate in 
front, the distal 2 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, 
