4 o DISCOVERY REPORTS 



The lower of the two postero-lateral spines of the carapace is small and quite well developed in all 

 the Discovery specimens. In the smallest specimen the rostrum is 33-3 % of the total length from its 

 tip to the apex of the telson and in the other specimens it is 21-3% and 21-5% respectively. 



Distribution. G. gracilis is widely distributed in the tropical waters of the world. Apart from four 

 localities situated between 25°n'N. and 34 00' N. and one from central California (Ortmann, 

 1906), it has never been taken north of the Tropic of Cancer. In the southern hemisphere it has 

 never been taken south of 12 09' S. It has been recorded on many occasions in the North Atlantic 

 from the Canaries and Cape Verde Islands in the east (Fage, 1941); from the Gulf of Guinea (Illig, 

 1930); from mid-Atlantic and from off the West Indies and south of the Bermudas (Fage, 1941). In 

 the Indian Ocean it has been recorded from north of Madagascar, the south of Ceylon and the Cocos 

 Isles (Fage, 1941) and from the Arabian Sea and the Bay of Bengal (Wood-Mason and Alcock, 

 1891 b). In the Pacific it has been recorded from many stations in the Gulf of Panama and around the 

 Galapagos Islands (Hansen, 1912; Fage, 1941); twice in mid-Pacific and many times around the 

 Philippines and East Indian Archipelago (Fage, 1941). 



It has never, up to the present, been recorded from the South Atlantic and its capture at two stations 

 to the N.E. and N.N.E. of St Helena considerably extends its known geographical range. 



G. gracilis is essentially bathypelagic in habit. All the records of it are from between 1 500 m. and 

 2000 m., with the exception of two very young individuals, recorded one by Fage and one by Hansen, 

 which were taken at about 800 m. By comparing the size of adult females captured in various parts 

 of the world, Fage (1941) discovered that there is considerable diversity in the length at which sexual 

 maturity is attained in different localities. In the Pacific, and especially in the eastern Pacific, females 

 were ovigerous at only 39 mm., while in the Indian Ocean they were still immature at 53-92 mm. 

 In the Atlantic females of 84-95 mm - an d ev en 100 mm. still had very small oostegites. 



Genus Lophogaster M. Sars, 1857 

 1857 Lophogaster M. Sars, p. 160. 

 1862 Ctenomysis Norman, p. 151. 



Remarks. Workers in the past have had difficulty in deciding which characters could best be used 

 in identifying the species of the genus Lophogaster. Most of these characters have subsequently been 

 shown to be very variable, and specimens differing considerably from one another and collected 

 from widely separated localities have been incorrectly referred to the type species L. typicus. Fage 

 (1942, pp. 7-39) and Tattersall (195 1, p. 16), have done much to clear up the existing confusion. 



Four species of the genus are represented in the Discovery collection : L. challengeri Fage, L. spinosus 

 Ortmann, L. rotundatus Illig and L. schmidti Fage. 



Lophogaster challengeri Fage, 1942 



(Fig. 2A-D) 

 18856 Lophogaster typicus G. O. Sars, p. 14, figs. 

 1942 Lophogaster challengeri Fage, p. 16, figs. 



Occurrence : 



St. 277. 7. viii. 28 (night). Just off Cape Lopez. Two hauls: (i) 63-0 m., 8 juv., 5-5-5 mm., 3 juv. 4 mm.; (ii) 88- 



o m., 4 juv. 5-6 mm. 



St. 279. 10. viii. 27 (day). Just north of Cape Lopez, 58-67 m., 1 juv., 8 mm., 3 juv. 3-5 mm. 



St. 424. 4. ix. 30 (night). Off Port Elizabeth, 59-0 m., 1 juv. 7-6 mm., 1 juv. 8-4 mm. 



St. 443. 23. ix. 30 (night). South of Knysna, South Africa, 49-0 m., 1 imm. 115 mm. 



St. 444. 24. ix. 30 (night). South-west of Cape Peninsula, 80-0 m., 1 juv. 8 mm. 



St. 844. 8. iv. 32 (night). South of Cape Town, 155-0 m., 1 juv. 8 mm., 1 juv. 7-6 mm. 



