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.) 

 IpMmedia echinata, A. 0. Walker, Ann. and Mag. Nat. Hist. XVIII. (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 carinas, 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 ; ei/es prominent, round, colourless. 



Upper antennse : 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 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 setae. First joint of the flagellum as long as the next three.* 



Lowei' antemise 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, difierent ; 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. 



