REPORT ON THE DEEP-SEA FISHES. 315 



tubes, which are sac-shaped, and which commence on the posterior lobate margin and run 

 forwards, converging at the same time to a point in the median line near the anterior 

 margin. These tubes are filled with the ordinary spherical gland-cells. 



c. Function. 



The light-reflecting spicule-layer renders it sufliciently certain that this organ is 

 phosphorescent. It illuminates the water in front of and below the fish. 



9. Differentiated barbels and fin-rays. 



a. Distribution. 



The extraordinary barbels of Opostomias viicripnus (PL LXXII. fig. 39) and Pachij- 

 stomias microdon, which are either attached to the mouth or developed from the first ray 

 of the pectoral fin, bear on their distal portion the organ to be described below. 



h. Structure. 



This organ is attached to one side of the barbel only. It consists of gland-tubes 

 which a^jpear closed on all sides, and which are straight and conical, tapering j^roximally 

 (PI. LXXII. fig. 36). These tubes are perpendicular to the surfiice of the barbel. As 

 the central gland-tubes are the longest, the whole structure has a very oblong, oval 

 transverse section. They are covered by a granular layer which forms a kind of sheath 

 to the whole organ, and which extends beyond the base' of it, so as to enclose the 

 opposite side of the liarbel with a thin film (PI. LXXII. fig. 36). 



c. Function. 



The gland-tubes are in every respect very similar to those found in some of the 

 undoubtedly phosphorescent organs of fishes and it may therefore be assumed that they 

 emit light. The only use to which they might be put would be to act as lures to 

 attract other animals. 



10. Glandular organs under the gill-covers. 



a. Distnbution. 



These organs are only found in Haldsaxiru.'i macrochir, where they form a con- 

 spicuous white patch just behind the last gill-arch in the clavicular region on each side 

 of the fish. 



