GEMPYLIDAE 



97 



This is the species known in South Africa as " Snoek", in Australia and New Zealand 

 as " Barracouta", and in Chile as "Sierra". 



^jgSMSimzz^ 



Fig. 48. Thyrsites atun. x J. 



SCOMBRIDAE 

 Genus Gasterochisma, Richardson 



1845, Ann. Mag. Nat. Hist., xv, p. 346; Richardson, 1S46, Zool. 'Erebus' and ' Terror', Fishes, 

 p. 60; Regan, 1902, Ann. Mag. Nat. Hist. (7) x, p. 120. Type G. melampus, Richardson. 



Lepidothynnus, Giinther, 1889, Pelagic Fish. 'Challenger', p. 15. Type L. huttoni, Giinther. 



Chenogaster, Lahille, 1903, Anal. Mus. Nac. B. Aires, ix, p. 375; Lahille, 1905, Anal. Mas. 

 Nac. B. Aires, xi, p. 461. Type C. holmbergi, Lahille. 



The systematic position of this genus is clearly with the Scombridae rather than with 

 the Stromateidae, as has been shown by Regan. There is probably only a single species. 



Gasterochisma melampus, Richardson. 



Gasterochisma melampus, Richardson, 1845, Ann. Mag. Nat. Hist., xv, p. 346; Richardson, 1846, 

 Zool. 'Erebus' and ' Terror', Fishes, p. 60, pi. xxxvii, figs. 1-3 ; Regan, 1902, Ann. Mag. Nat. 

 Hist. (7) x, p. 120; Stead, 1907, Add. Fish-Fauna N.S. Wales [1], p. 21, pi. vi; Waite, 1913, 

 Trans. N. Zeal. Inst., xlv, p. 220, pi. viii; McCulloch, 1922, Austral. Zool, 11, p. 104, 

 pi. xxxiii, fig. 287a; Phillipps, 1927, N. Zealand Mar. Dept. Fish. Bull, 1, p. 45. 



Lepidothynnus huttoni, Giinther, 1889, Pelagic Fish. 'Challenger', p. 15, pi. vi, fig. A. 



Chenogaster holmbergi, Lahille, 1903, Anal Mus. Nac. B. Aires, ix, p. 375; Lahille, 1905, Anal 

 Mus. Nac. B. Aires, xi, p. 461, pi. i. 



Gasterochisma boulengeri, Lahille, 1913, Anal. Mus. Nac. B. Aires, xxiv, p. 8, pis. iii, iv, 

 text-fig. 2. 



Hab. Southern Atlantic and Pacific Oceans. 



No specimens of this interesting oceanic species were obtained by the Discovery 

 Expedition, but Mr Hamilton has sent portions of a damaged skeleton from the 

 Falkland Islands, together with a photograph of a stuffed specimen, nearly 4 feet in 

 length, in the museum at Stanley. This specimen is from West Point Island. There are 

 also some scales, sent to the British Museum by Mr R. Vallentin in 191 1, taken from 

 a fish from the north-west corner of West Falklands. The type of G. melampus is about 

 200 mm. in total length, that of G. boulengeri was 725 mm., that of Chenogaster holmbergi 

 was about 1550 mm., and that of Lepidothynnus huttoni was about 1680 mm. These 

 specimens form a complete series, and I have no doubt that they represent different 

 stages in the growth of a single species. A similar change in the size of the pectoral, 

 and particularly of the pelvic fins, with age, is met with in such genera as Nomeus, 

 Psenes, Leirus, etc. 



