SURVEY OF STRUCTURE 



37 



Diaphus dofleini Zugmayer (Text-fig. 20 A, b) 



St. 250, 36 09' 00" S., 5° 33' 00" W., 17. vi. 27, TYF, 3<x>(-o) m. B.M. Reg. no. 1930. 1. 12. 831-2. Standard 

 length 32 mm. (6-5 x 1-5 mm.). 



This lantern fish has a thin-walled swimbladder, which originates over the forepart of the stomach 

 and spans nearly two-thirds the length of the body-cavity. The retia mirabilia arise to the right of the 

 lower surface of the sac, about 1 mm. behind its forward end. Each rete is nearly 1-5 mm. in length. 

 The three lobes of the gas-gland, which invest the middle part of the swimbladder floor, are roughly 

 oval in outline and measure 2-5 and 1 mm. in length and breadth. 



Text-fig. 20. Swimbladders of Diaphus dofleini (a and b) and D. garmani (c). A and c are lateral views; B is a ventral view. 

 gg, gas-gland ; int, intestine ; k, kidney ; ov, oval ; oy, ovary ; pc, pyloric caecum ; rm, rete mirabile ; st, stomach, (a, x 8 ; B, x 10 ; 

 c,x8-5.) 



Just above the point of origin of the retia and on the right side of the sac, the oval appears as a 

 circular cap (about 0-75 mm. in diameter). It is partly open, the capillary-bearing part being sur- 

 rounded by a ring of connective tissue containing circular and radial muscle fibres. 



Diaphus garmani Gilbert (Text-fig. 20 c) 

 B.M. Reg. no. 1934.5.4. I_2 - Montserrat. Standard length 34-5 mm. (6-o x 2-0 mm.). 



A thin-walled swimbladder was found just above the stomach. The three retia mirabilia are bound 

 together in a club-shaped forward extension of the swimbladder. They are about 1 mm. in length 

 and supply a rather small gas-gland. This extends over the floor and lateral walls of the foremost 

 quarter of the organ. 



Diaphus luetkeni (Brauer) 



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 34 mm. (3-5 x 1-2 mm.). 



As the swimbladder of this fish was relaxed, the walls appear thick, while the gas-gland occupies 

 most of the floor. When the sac is expanded, the dimensions must be considerably more than those 

 given above. 



