72 DISCOVERY REPORTS 



Since all these animals with unusually large eyes come from the waters off South Georgia, I suggest 

 that they may represent a geographical race. All the specimens except those from station WS 29 

 are fully adult and are considerably larger than adults from other localities — their average length 

 being 22-47 mm - compared with an average of about 18 mm. from other stations. 



Boreomysis illigi sp.n. 

 (Fig. 1 1 B-E) 

 1930 Boreomysis rostrata Illig, pp. 214-19, figs. 28-35 {<$$ only). 



Occurrence : 



St. 87. 25. vi. 26 (day). West of Cape Town, iooo(-o) m., 1 imm. $, 14 mm. 



St. 298. 29. viii. 27 (day). West of Cape Verde, i200-90o(-o) m., 1 imm. <£, 2 adult $$, 16 mm. (Colour note, 'Clear 



scarlet throughout'.) Types. 

 St. 696. 12. v. 31 (day). Between Cape Verde Is. and St Paul's Rock, 1000-750 m., 1 badly damaged imm. $. 

 St. 1602. 27. x. 35 (night). West of Cape Frio, 470-300 m., 2 imm. $$. 

 St. 2034. 6. iv. 37 (night). West of Cape Town, 162-0 m., 1 damaged ?, 16 mm. 



Description. Rostrum acutely pointed with the lateral margins convex for most of their length but 

 concave near the distal end; extending forward slightly beyond the middle of the eyes (Fig. 11 B, C). 

 Eyes well-developed; papilla very long, extending forward beyond the anterior margin of the cornea 

 (Fig. 1 1 C). Antennal scale four times as long as broad at its widest part ; outer margin slightly sinuous ; 

 apex well-developed and extending beyond the tooth which terminates the unarmed outer margin 

 (Fig. 1 1 D). Thoracic appendages small and slender; distal portion of the endopod of the second pair 

 not prehensile but exactly as figured by Illig (1930, p. 417). Uropods long and slender; exopod longer 

 than the endopod; unarmed portion of the outer margin nearly one-fifth of the total length, ter- 

 minated by two small unequal spines, the inner nearly twice as long as the outer; endopod slightly 

 longer than the telson, armed with two long slender spines on the inner margin distal to the statocyst 

 (Fig. 11 E). Telson three times as long as broad at the base; spines arming the lateral margins slightly 

 unequal, but with no trace of the eight or ten very long spines which are present in B. rostrata; 

 cleft deep and narrow, one-fourth of the length of the telson in depth, base of the cleft without the 

 lateral notches, which produce the characteristic dilatation at the proximal end of the cleft of the telson 

 in B. rostrata (Fig. 1 1 E). 



Length of adult female, 16 mm. ; none of the males is adult. 



Colour. Clear scarlet throughout. 



Remarks. When Illig (19060, p. 196; 1930, pp. 414-19) founded the species B. rostrata, he recorded 

 and figured quite considerable differences between the males and the females. He regarded these as 

 sexual variations. Later workers considered that these differences were too fundamental to be 

 explained on these grounds and it has long been felt that Illig was really dealing with two distinct 

 species. W. M. Tattersall (1951, p. 58) accepted Illig's female specimens as the types of B. rostrata, 

 but considered that the males should be referred to another species, although he did not suggest 

 a name for it. 



In the Discovery collections there are a few specimens of both sexes, which agree remarkably closely 

 with the description and figures given by Illig for the male of B. rostrata. The larger females are 

 adult with the brood sac fully developed and the males, though not mature, are sufficiently well- 

 grown to show that there are no appreciable differences between the sexes, and to leave no doubt that 

 they belong to the same species, which is distinct from B. rostrata. I suggest that these specimens 

 should be placed in a new species under the name of B. illigi, since I regard the males of Illig's 

 B. rostrata as the prototypes of the species. 



