SURVEY OF STRUCTURE 



45 



Reference to Text-fig. 25 will show the small volume of the lumen compared with the total volume 

 of the sac. Between the inner epithelium and the tunica externa is a voluminous layer of lamellar 

 fibres belonging to the submucosa, which thus makes up most of the total volume. Clearly this is 

 a regressed swimbladder, which is doubtless relatively better developed during the early life-history. 



In having a swimbladder with clearly separate glandular and resorbent parts, Stylophorus is 

 evidently an euphysoclist. But it is unusual in having these two parts reversed in position, for in most 

 euphysoclists (without an oval) the fore part is secretory, while the rear part is resorbent. 



Text-fig. 26. Swimbladder of Stephanoberyx monae, seen (a) from above. In (b) is shown the blood supply to the right lobe 

 of the gas-gland, cl, capillary hop; gg, gas-gland; ov, oval; rm, rete mirabile. (a, x 5-5; b, x 17.) 



Order BERYCOMORPHI 



Family Stephanoberycidae 



Stephanoberyx monae Gill (Text-fig. 26) 



Oregon St. 1426 (29 07' N., 87 54' W.), 24. ix. 57, 600 fathoms, trawl. Standard length 83-5 mm. (16-0 x 8-o mm.). 



The swimbladder of this species is ellipsoidal in form and extends down most of the length of the 



upper part of the body-cavity. 



The blood supply for the retia enters the floor of the sac close to its posterior end. The artery and 

 vein form two long retia mirabilia (about 8 mm. in length). In the fish dissected the retia were dis- 

 placed in position, but presumably extend forward along the swimbladder floor. Each rete runs to 

 a corresponding lobe of the gas-gland, where the capillaries form loops running through the secretory 

 tissue. The retia are thus unipolar in structure. 



Immediately above this point of entry of the retial blood supply there is an oval on the roof of the 

 sac. This measured about 5 mm. in diameter and was partly closed. The capillary network of this 

 resorbent structure was plainly visible under the high power of a binocular microscope. 



