268 



DISCOVERY REPORTS 



in a longitudinal series. Dorsal 15 ; anal 15 ; both fins originating at about the same level. 

 Pectoral with 13 or 14 rays, broad-based, rounded, shorter than eye. Uniformly 

 blackish; fins pale. 



Described from a single specimen, 90 mm. in length. 



Hab. North and South Atlantic. 



This genus seems to be well distinguished from Alepocephalus by the form of the 

 gill-membranes, the smaller number of branchiostegal rays, the nature of the dentition, 

 and the broad-based, rounded pectoral fin. 



Bathytroctes (Bathytroctes) rostratus, Giinther, 1878. [PI. II, fig. 3.] 



Bathytroctes rostratus, Holt and Byrne, 1908, Fisheries, Ireland, Set. Invest. 1906, v, p. 45, pi. iv, 

 figs. 3-5. 



St. 86. 24. vi. 26. 33° 25' 00" S, 6° 31' 00" E. 4I m. net, horizontal, 1000 (-0) m. : 2 specimens, 

 30-47 mm. 



St. loi. 14-15. X. 26. 33° 50' to 34°i3'S, 16° 04' to i5°49'E. 42 m. net, horizontal, 350- 

 450 (-0) m. : 2 specimens, 30-40 mm. 



I have identified these young examples with Bathytroctes rostratus, Giinther, after 

 some hesitation, as it is difficult to compare them accurately with the type, which is 

 considerably larger. They agree very 

 closely, however, with the small speci- 

 mens described by Holt and Byrne 

 under this name. All exhibit the pig- 

 mented "supraclavicular process", 

 and there is no sign of this diminishing 

 in size in the largest of the specimens 

 collected by the 'Discovery'. I count 

 1 9 to 20 rays in the dorsal fin, and 14 

 to 16 in the anal. No mention is made 

 by Holt and Byrne of the small oval 

 luminous organs, which in the pre- 

 served specimens appear as white 

 spots. They are regularly arranged, 

 and seem to disappear altogether in 



the adult fish. A coloured sketch of the ^ig. i. Outline drawings of three young specimens of 

 ventral surface of one of the specimens Bathytroctes (Bathytroctes) rostratus, respectively 30, 40 and 

 fromSt.86,madebyMrE.R.Gunther 47 mm. in length, (x i|.) A portion of the ventral surface 



of the largest specimen is included to illustrate the arrange- 



(Pl. II, fig. 3), shows the luminous 



ment of some of the principal luminous organs. 



organs red in colour in the fresh fish, 

 although some of those which had been damaged appeared white. Their arrangement 

 has been well described by Brauer (' Valdivia' Tiefsee-Fische, p. 17, pi. xiv, figs. 2-3), 

 and is shown in the accompanying figures. Between the pelvic fins is a deeply pigmented 

 globular body, with a luminous spot on its anterior and posterior surfaces. 



