28 A. 0. WALKER. 



The tooth on the first joint of the upper antennae 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.) 

 Iphimdia echinata, A. 0. AValker, Ann. and Mag. Nat. Hist. XVIII. (1906), p. l. r >0. 



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 carinse, 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 

 segment 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 antennae : First joint 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 fiagellum 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 setae. First joint of the flagellum as long as the next three.* 



Lower antennae subequal to the upper ; second and third joints subequal ; the 

 three peduncular joints 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. 



* In the specimen figured the antenna was curved upwards. 



