42 DISCOVERY REPORTS 



which I have examined, the post-orbital spine is so marked, even in juveniles, that it cannot be 



overlooked. 



The spines at the postero-lateral angles of the carapace are larger than in L. typicus and as a result 

 of the greater concavity of the dorsal margins of the free carapace lobes, they are directed somewhat 

 upward (Fig. 2B). In L. typicus they are horizontal and so small that they can hardly be regarded as 

 spines at all. 



The lobes from the inner distal margins of the third segment of the antennular peduncle are well 

 produced and evenly rounded at their anterior end, their margins smooth and each armed with a single 

 small bristle (Fig. 2 A). 



The small apical plate between the two large apical spines of the telson is very pronounced and 

 much longer than recorded by other workers, but this may be a sign of immaturity (Fig. 2C-D). 



The length of adults of this species has been recorded as 25 mm. for males and 24 mm. for females. 



Distribution. L. challengeri is essentially a coastal, shallow-water form. It has usually been taken 

 at depths of 150-50 m. but has been captured at 274 m. It appears to prefer temperate conditions 

 and the fact that it was taken by 'Discovery' as far north as Cape Lopez may be due to the cold 

 waters of the Benguela Current. The Challenger specimens (referred to L. typicus by G. O. Sars) 

 were taken off the south coast of South Africa. 



Lophogaster spinosus Ortmann, 1906 



1906 Lophogaster spinosus Ortmann, p. 26, figs. 



1914 Lophogaster spinosus, Zimmer, p. 382. 



1926 Lophogaster spinosus, Tattersall, p. 7 and 1937, p. 1. 



1942 Lophogaster spinosus, Fage, p. 23, figs. 



1 95 1 Lophogaster spinosus, W. M. Tattersall, p. 21. 



Occurrence : 

 St. 679. 29. iv. 31 (night). East of Rio de Janeiro, 300-0 m., 1 imm. (measured from tip of rostral spine to apex 



of telson) 14-4 mm., 1 small juv. 

 St. 680. 30. iv. 31 (night). South of Ilha da Trinidade, 260-0 m., 2 small juv. (one with telson missing). 



Remarks. This species can readily be recognized by its extremely long, strong median rostral 

 spine, by the very long spinous prolongation of the postero-lateral angles of the carapace, by the long 

 spines on the postero-lateral angles of the tergum of the last abdominal somite and, especially, by 

 the long triangular shape of the antennal scale with its almost straight internal margin. Tattersall 

 (195 1, p. 21) recorded that the postero-lateral spines of the carapace extend backward to 'the end of 

 the second abdominal somite in the smaller specimens and to the end of the third abdominal somite 

 in the larger specimens '. None of the Discovery specimens is mature, but in the largest, these spines 

 extend well beyond the posterior margin of the second abdominal somite. The length of this specimen 

 is 14-4 mm. from the tip of the rostrum to the apex of the telson and, since the type specimen measured 

 39 mm., it is obviously far from adult. 



Distribution. L. spinosus has been recorded from the northern hemisphere at various stations in 

 the West Atlantic between 34 N. and 19 N. and in the southern hemisphere in mid- Atlantic between 

 16 54' S. and 3 21' S. The two stations at which it was taken by 'Discovery II ' are west of the sta- 

 tions from which it has previously been recorded in the South Atlantic. Both stations are far out to 

 sea to the east of Rio de Janeiro (lat. 30 W.). Fage pointed out (1942, p. 25) that, although one cannot 

 state categorically that it does not occur in equatorial waters, it is significant that 'Dana' in 1941 

 made collections at eighteen stations, while crossing the Atlantic from Cape Verde to Guiana, without 

 taking a single Lophogaster. L. spitwsus, in contrast to all the other species of the genus, inhabits the 



