34 



DISCOVERY REPORTS 



Hygophum benoiti (Cocco) (Text-fig. 17) 

 B.M. Reg. no. 85.6.22. 120-9. Straits of Messina. Standard length 4-1 mm. (7-0 x 2-0 mm.). 



The swimbladder of this lantern fish is both thin-walled and capacious. At the anterior end three 

 retia mirabilia run into the gas-gland, which covers most of the floor and side walls of the forward 

 half of the organ. Each rete has a length of nearly 3-0 mm. 



Over the point of entry of the retia mirabilia into the gas-gland and rather to the right of the swim- 

 bladder is a forward conical extension (the distorted oval) receiving a rich supply of blood-vessels. 

 Within the oval the walls are thrown into a series of longitudinal ridges. 



Text-fig. 17. Swimbladder of Hygophum benoiti, seen (a) laterally, and (b) ventrally. gg, gas-gland; ov, oval; 



rm, rete mirabile. (a, x 13-5 ; b, x 19.) 



Benthosema glaciale (Reinhardt) (Text-fig. i8d-f) 



Position, 13° 25' N., 18 22' W., 28. x. 25, N 450 V, 90o(-o) m. B.M. Reg. no. 1930. 1. 12. 641-7. Standard length 

 of fish 45-5 mm. B.M. Reg. no. 1911.2.8. 3-12. Between Faroes and S.W. Ireland. Standard length of fish 

 58-5 mm. 



The swimbladder of this myctophid is thin walled and lies above the stomach. In the 45-5 mm. 

 fish it measured 5-5 mm. in length and about 2 mm. in depth and width at the middle region. A 

 bulbous projection at the fore-end of the bladder contains the three retia mirabilia, which run back- 

 wards to a gas-gland investing much of the floor and side walls. Each rete has a mean length of 

 about 3 mm., the two outer systems being rather longer than the middle. 



Just behind the base of the bulbous forward projection and on the left-hand side of the swimbladder 

 is a small rounded chamber (the oval) receiving many blood-vessels. The oval has a sphincter-con- 

 trolled opening into the main cavity, while the walls are thrown into radially disposed folds. In the 



