194 THE RADIATING ORGANS OF THE DEEP SEA FISHES. 



The suborbital radiating organs (Plate 10, Fig. 47 so) are represented 

 by Gnrman in his figure ('99, Plate 56, Fig. 3), but not mentioned in his 

 description ('99, ]ip. 276, 277). The snborbital organ lies below and behind 

 the eye ; it apjjears nearly s[)herical, is 8(10 /x in diameter, and enclosed 

 in a pigment sheath and a connective-tissue capsule. The pigment sheath 

 forms a sac, the opening of which abuts on the surface of the fish. It is 

 composed of concentric layers of rather loosely scattered cells containing 

 brown pigment. Within this pigment sheath lies the connective-tissue cap- 

 snle. The structure of the inner cell mass could not cleai-ly be made out, as 

 these organs were somewhat injured in the s[)eciniens at my disposal. 



The simple radiating organs without pigment sheath appear as small 

 white dots 100 /x in diameter. They are scattered in great numbers over 

 the ventral side of the lish and also occur in the three terminal threads of 

 the barbel mentioned above. They are juoie or less s])lierical, enclosed in 

 connective-tissue capsules and composed of pretty large radially arranged 

 cells with conspicuous luiclei. 



The simple radiating oi'gans with pigment sheath are met with on the 

 hexagonal scales of the body and also on the head of the fish. They appear 

 as dark spots and measure 300^ in diameter. On each ventral scale a 

 group of 7 of these organs occurs, upwards they gradually become scarcer; 

 and near the dorsal medial line of the fish only one such organ is found on 

 each scale. In their structiu'c these organs resemble the simple radiating 

 organs with pigment sheath of Chmdiodus harbatti^ described above. The 

 hyaline mass which in the latter covers the organ outside, is, however, 

 absent in these organs of Stomias hexagonalus. 



The compound radiating org.ans with pigment sheath (Plate 10, Figs. 47, 

 48, 49, 51) appear as conspicuous dots with a silvery lustre ajid are 300- 

 500 /x in diameter. On tlie whole they are largest in front and decrease in 

 size backwards. There are on each side of the body 12 guttural (Plate 10, 

 Figs. 47, 48 g), 16 branchiostegal, 38 ventrothoracic (Figs. 47, 48 vt), above 

 these in a parallel row 37 anterior lateral (Figs. 47, 48 al), 10 venfiomedial 

 (Figs. 47, 48 ve), 10 medial lateral (Figs. 47, 48 ml), and 19 ventroanal 

 (Figs. 47, 48 a) compound radiating organs with pigment sheath. 



Two different kinds of these organs can be distinguished. The first 

 somewhat larger kind is represented by the anterior compound organs of 

 the body which form the ventrothoracic and anterior lateral rows. All the 

 other compound organs belong to the second, smaller kind. 



