3 6 DISCOVERY REPORTS 



Not far behind the forward tip and on the right-hand side of the bladder, the oval, which is almost 

 closed, appears as a small circular blister, about 0-3 mm. in diameter. This has a small opening into 

 the main cavity and the much folded walls have a rich supply of blood capillaries. 



Diogenichthys atlanticus (Taning) 



St. 288, oo° 56' 00" S., 14 08' 30" W., 21. viii. 27, TYF, 25o(-o) m. B.M. Reg. no. 1930.1.12. 846-7. Standard 

 length 25-5 mm. (3-0 x o-6 mm.). 



The swimbladder of this specimen was in a relaxed state, the walls appearing thicker than they 

 would be when the sac is inflated. The three retia mirabilia are bound together in a bulbous forward 

 extension and are closely followed by the gas-gland, which covers about three quarters of the swim- 

 bladder floor. 



Myctophum humboldti (Risso) 

 St 1566, 40 42' S, 36 05-5' E., 9. iv. 35, N 70 H, 0-5 m. Standard length 50 mm. (8-0x4-0 mm.). 



This species has a capacious thin-walled swimbladder. The three retia mirabilia run underneath 

 the forward, rounded end of the swimbladder to the gas-gland, which is three lobed and extends over 

 the floor and lateral walls. Each rete is about 3 mm. in length, while the gas-gland has a length of 

 about 2-5 mm. and a width (when flattened out) of about 4-5 mm. 



Myctophum affine (Liitken) (Text-fig. 19) 



St. 694, 04 05!' N.,-30° 00' W., 10. v. 31, NH, o m. B.M. Reg. no. 1948.5. 14. 234-6. Standard length 51 mm. 

 (9-0 x 4-0 mm.). 



Text-fig. 19. Swimbladder of Myctophum affine, seen (a) in body-cavity, (b) ventrally (anterior end), and (c) laterally (anterior 

 end), gg, gas-gland; int, intestine; ov, oval; ra, retial artery; rm, rete mirabile; st, stomach; vov, vein to oval, (a, x^-^; 

 b, X25; c, X25.) 



The swimbladder is thin walled and extends down some three-quarters of the length of the body- 

 cavity. The retia mirabilia extend back from the foremost tip of the sac and run to an oval-shaped 

 gas-gland lying on the floor of the anterior half. The gland measured 1-5 mm. in length and 1-25 mm. 

 in width, while the retia spanned about 1-5 mm. 



To the left of the forward end of the swimbladder is the oval, which is closed, and appears as a 

 wrinkled projection with thick, expanded walls. 



