4 6 



DISCOVERY REPORTS 



Family Melamphaidae 



Melamphaes megalops Liitken (Text-fig. 27) 



St. 13° 25' N., 18° 22' W., 28. x. 25, 44-m. net, horizontal 90o(-o) m. Standard length 56 mm. (8-5 x 5-0 mm.). 



In this species there is a capacious swimbladder which, when fully inflated, must occupy about 

 three-quarters of the length of the upper part of the body-cavity. 



Text-fig. 27. Swimbladder of Melamphaes megalops, seen (a) in fish ; (b) ventrally, and (c) dorsally (posterior end). The 

 oval is shown in (d). cm, circular muscles of oval ; gg, gas-gland ; op, opening of oval into cavity of swimbladder ; ov, oval ; 

 ram, radial muscles of oval; rm, rete mirabile. (a, x 1 ; b, x 10; c, x 5 ; d, x 25.) 



At the posterior end of the sac, an artery and vein run forward to supply a single rete mirabile, 

 which measures about 1 2 mm. in length. After its formation the rete runs backwards but soon bends 

 sharply to run along the right-hand side of the gas-gland. Having reached a point ahead of the 

 forward edge of the gas-gland, it turns back to enter the gland. Here it separates into capillary loops 

 that meander among the secretory cells. As in Stephanoberyx, the rete is unipolar. An extensive 

 gas-gland covers the median part of the swimbladder floor, the length and breadth being about 3 mm. 



Just in front of the posterior tip and on the roof of the sac is an oval (about 2 mm. in diameter), 

 which was almost closed, the entry into the sac measuring about 0-5 mm. in width. 



The circular sphincter muscles that close the oval could be seen around the rim of the opening, 

 where they are crossed by the long relaxed fibres of the radial complex. When these contract, the oval 

 is expanded, the capillary network then being fully exposed to the gases in the swimbladder. During 

 this phase gases are free to diffuse into the blood. 



