SURVEY OF STRUCTURE 35 



Discovery fish the chamber was about 0-5 mm. in diameter and the inner opening, which was oval, 

 measured 0-5 x 0-3 mm. The corresponding figures for the other fish are o-6 and 0-2 x 0-2 mm. 



In both fishes the anterior part of the swimbladder was entirely invested by fatty tissue, which 

 extended under the organ (and beyond it in the larger individual). 



Text-fig. 18. Swimbladders of Benthosema suborbitale (a, b, c), and B. glaciate (d-f). a, c, d, e, lateral views; b, dorsal view. 

 The almost closed oval of B. glaciale is seen in diagrammatic transverse section and from below in (f). bl, urinary bladder; 

 gg, gas-gland; int, intestine; k, kidney; ov, oval; oy, ovary; ra, retial artery; rv, retial vein; rm, rete mirabile; st, stomach; 

 vov, vein to oval, (a, x 11-5; b, x 15; c, x 15; d, x 11 ; e, x 10; f, x 20.) 



Benthosema suborbitale (Gilbert) (Text-fig. i8a-c) 



St. 2067, 24°i2'N., 21 12-2' W., 12. v. 37, N450H, 68(-o) m. B.M. Reg. no. 1948.5. 14. 185-91. Standard 

 length of fish 24 mm. (4-3 x 1-3 mm.). 



A thin-walled swimbladder originates over the forepart of the stomach and extends over some 

 two-thirds of the length of the body-cavity. 



The gas-gland invests the floor of the foremost third of the organ. As in all myctophids, the gland 

 receives three retia mirabilia, which enter the anterior and lower part of the swimbladder. 



5-2 



