528 PERCY SLADEN TRUST EXPEDITION. 
the telson truncate with the angles more or less rounded. In the last respect some 
specimens approach L. cinghalensis, Stebbing, so closely that, not being able to detect 
any other valid difference, I am compelled to doubt whether this species is distinct. 
L. bispinosa (Della Valle) differs from JZ. ceratina only in the colouring of the 
integument and (judging from the figure) the number of joints in the accessory 
flagellum of ant.1, neither of which characters is of much value. Some of the specimens 
taken in Ceylon (Amphipoda of Pearl Oyster Fisheries, p. 242), and named L. cinghalensis, 
doubtless are this species. 
The following synopsis of the species may be useful :— 
Synopsis of Lysianassa. 
Eyes red or red-brown, often fading in spirit . 2. 
pees dark brown or black, not fading in spirit 4. 
ms Telson squared apically with a central notch . L. punctata (Costa). 
“*| Telson apically elliptical 3 3. 
Hind angle of pleon segment 3 sche a pféniinent distal eobthh 
3.4 on the Ist joint of ant. 1 : : L. longicornis, Lucas. 
Hind angle of pleon segment 3 uphipaed and acute L. plumosa, Boeck. 
Hind angle of pleon segment 3 rounded 5. 
2 Hind angle of pleon segment 3 upturned . L. variegata (Stimpson). 
{ Telson apically elliptical 6. 
¥ |v Telson apically truncate . : F The 
Palm of 6th joint of 2nd gnathopod Pe concave L. celochir (A. O. W.). 
2 ee of 6th joint of 2nd gnathopod not deeply concave : L. cinghalensis (Stebb.). 
Antenna 1: Ist joint smooth; inner ramus of 2nd uropod dilated . L. cubensis (Stebbing). 
“aes Antenna 1: Ist joint with 2 short apical teeth . L. ceratina (A. O. W.). 
4. Lysianassa cinghalensis (Stebbing). 
J. Amirante I.: Plankton, gg, surface. One male 4 mm. 
Genus ICHNOPUS, A. Costa, 1853. 
5. Ichnopus serricrus, sp.n. (Plate 48. fig. 1.) 
J. Amirante: dredged E 10, 22-85 fms.: one ¢. Coco I., Cargados: Plankton, ¢, 
surface: one ¢. 
Head longer than segment 1. Lateral angles produced, rounded. 
Pleon segment 3: hind margin convex, lower almost straight with a small tooth at 
the hind angle. 
Eyes very large, almost meeting above, elongate-reniform, dark. 
Ant. 1 reaching to seg. 5: 1st joint with a distal tooth below; flagellum more than 4 
times as long as peduncle, with 25 calceoliferous joints ; accessory flagellum longer than 
peduncle, 9-jointed. 
Ant. 2. Upper margin of the 2nd joint produced: flagellum about as long as the 
animal, without calceoli. 
Gnathopod 1. Side plates rather deeper than the width at the bottom, front margin 
concave. Second joint rather wider than the 3rd, which is subequal in length and width to 
