62 DISCOVERY REPORTS 



St. WS 229. 1. vii. 28 (day). North-east of Falkland Is., 210-271 m., 3 <Jc?> 2 $? (1 ovig.), 23 imm., largest adult 



15 mm. 

 St. WS 233. 5. vii. 28 (day). North-east of Falkland Is., 185-175 m., 1 $, 12 mm. 

 St. WS 234. 5 vii. 28 (night). 195-207 m, 2 $£, 1 $, 36 imm. (largest adult 12 mm.). 



St. WS 236. 6. vii. 28 (dusk to night). North of Falkland Is., 272-300 m., 2 S3, larger 12-2 mm., 7 $$, largest 13-5 mm. 

 St. WS 239. 15. vii. 28 (night). West of Falkland Is., 196-193 m., 1 $, 12 mm. 



St. WS 244. 18. vii. 28 (day). West of Falkland Is., 253-247 m., 2 <$<$, 2 ?$, 2 imm., largest adult 12 mm. 

 St. WS 245. 8. vii. 28 (night). South-west of Falkland Is., 304-290 m., 1 damaged $ probably about 14 mm. 

 St. WS 748. 16. ix. 31 (night). Magellan Strait, 30o(-o) m., 4 <$£, 11-2 mm.; 3 juv. $$ about 10 mm.; 3 $$, 



12-8 mm.; 7 juv. $$ up to 10 mm. 

 St. WS 749. 18. ix. 31 (day). Magellan Strait, 4o(-o) m., 2 fragments. 



. x. 31. (day). North of Falkland Is., 291-298 m., 1 <J, 1 ?, 11-2 mm., not fully adult. 



. i. 32 (day). Patagonian Shelf, west-south-west of Falkland Is., 272-278 m., 3 $<$, 2 $$, all about 



. i. 32 (night). South of Falkland Is., 351-368 m., 1 ?, 15 mm. 



. i. 32 (day). Haul A, South of Falkland Is., 461-468 m., 1 ?, 14 mm. 



ii. 31 (dusk to night). South-west of Falkland Is., 503-534 m., 1 $, 15 mm., and 1 $ in two pieces. 



Description. General form very long and slender, not tapering markedly towards the posterior end. 

 Carapace short, leaving the whole of the last two thoracic somites exposed; anterior end evenly 

 convex with no rostral projection, but with a well-defined upturned rim ; antero-lateral angles bluntly 

 pointed and produced forward beyond the centre of the anterior margin ; carapace inflated anterior 

 to the well-marked cervical sulcus and rising to a definite peak in the median line just behind the 

 anterior margin. Posterior to the sulcus, the lateral regions of the carapace are thickened up to the 

 level of two longitudinal keels, which rise to a strong tooth-like projection in the middle of their 

 length and turn with a sharp angle at their anterior end to run downwards and forwards in a shallow 

 concave arc as seen in Fig. 9 A. The dorsal median region of the carapace is somewhat hollowed, but 

 there are two elevated portions which appear as blunt projections in lateral view. I can see no trace 

 of hepatic or gastric spines (Fig. 9 A). The anterior margins of the exposed thoracic somites are pro- 

 duced upwards and forwards, so that they override the posterior margins of the preceding somites. 

 Pleoti not so tapering posteriorly as in H. antarctica, first somite with the tergum thickened and raised 

 above the level of the neighbouring somites giving the appearance of a saddle ; sixth somite half as 

 long again as the fifth (Fig. 9 A). Antennular peduncle robust, with the first segment in both sexes 

 larger than either of the other two, and bearing at the proximal end of the dorsal surface a very well- 

 marked pit-like depression, similar to that found in other species of the genus. In H. falklandica this 

 peculiar organ shows three denser areas within the pit and these stain more darkly than the surrounding 

 tissues. From the region of the insertion of the antennule, a well-developed rounded flap projects 

 forward and forms a kind of shield or lid, partially covering the depression. The flagella are not very 

 long; in the female they are about equal in thickness, but in the male the proximal fourteen or fifteen 

 segments of the outer flagellum are enormously thickened and densely hirsute, especially on their outer 

 margins (Fig. 9 A-D). Antennal scale long and narrow, 6h times as long as broad and half as long again 

 as the antennular peduncle; outer margin armed with 9-10 strong spines among the setae; peduncle 

 four-fifths as long as the scale; second segment i-| times as long as the third; strong spine present on 

 the outer distal corner of the sympod (Fig. 9F). Eyes. The fleshy pad which represents the eyes is 

 relatively wider than in H. antarctica and the projecting distal corners more widely apart. The slightly 

 bilobed anterior margin of the head projects and can be seen below and a little beyond the distal margin 

 of the eyes (Fig. 9B). First thoracic appendage very similar in form to that of H. fyllae, consisting of 

 a short robust endopod and no exopod. The three large spines arming the distal end of the endopod 

 are unusually large and robust (Fig. 9G). Second thoracic appendage similar to that of H. fyllae 



