28 A. O. WALKER. 
The tooth on the first joint of the upper antennz is much longer in the large 
specimens than is shown in Stebbing’s figures. This is probably only a matter of age. 
IPHIMEDIA ECHINATA. (PI. 10, fig. 16.) 
Iphimedia echinata, A. O. Walker, Ann. and Mag. Nat. Hist. XVIIT. (1906), p. 150. 
W.Q., 24 Sept., 1902, Hut Point, one, large ; 24 Aug., 1903, Hole 12, D-net, three, 
large, 30 mm., and about twenty-five, young ; 26 Sept., 1903, Hole 12, D-net, one, about 
45 mm. long and 15 mm. across the back. 
First segment of the mesosome longer than the second ; the next four segments are 
longer than the second and subequal; the posterior angles of the first two are almost 
right angles, and of the next four acute. The fifth segment has sometimes a few small 
teeth on the hind margin ; the sixth has more, and the seventh is dorsally depressed, 
and is longer than any of the other segments in the middle, but greatly narrowed down- 
wards, with the hind margin more coarsely dentate. The pleon segments have 
strongly dentate, dorsal carine, with smaller teeth on each side, and on the hind 
margins ; the posterior angle of the second is acute and upturned, and that of the third 
similar, but longer, and with a much longer curved tooth above it. The first urus 
seoment is as long as the two next united, and has a dorsal depression followed by a 
group of upright teeth; the second and third are smooth, except for a tooth on each 
side of the telson. The first three pairs of side-plates narrow downwards to a point, 
the second and third curved; the fourth, fifth and sixth have a strong tooth with 
serrate edge directed outwards. The number of teeth appears to vary considerably in 
different specimens. 
Head: Rostrum as long as the rest of the head, acute, decurved ; ocular lobes 
rounded ; eyes prominent, round, colourless. 
Upper antenne: First jomt with two distal teeth on the upper side ; second joint 
with a serrate tooth reaching almost to the end of the first joint of the flagellum on the 
upper margin, and a short one on the lower; third joint short. In a young specimen 
a rudimentary appendage was seen, but in a larger (though not adult) this was only 
indicated by two sete. First joint of the flagellum as long as the next three.* 
Lower antenne subequal to the upper; second and third joints subequal; the 
three peduncular joits have the upper margins produced; the basal joint has a 
prominent curved tooth on its upper side. 
Mandibles, without molar tubercles, different; one, having the simple cutting 
edge oblique, obscurely dentate, with a tooth at the lower angle; the other having the 
cutting edge more strongly dentate, with a peculiar secondary apparatus in the form of 
a hollow chitinous cylinder with a smooth periphery. First joint of the robust palp 
shorter than the second, which is subequal to the third. 
* Tn the specimen figured the antenna was curved upwards, 
