192 THE RADIATING ORGANS OF THE DEEP SEA FISHES. 



sides of the head under tlie large suborbital organ with pigment sheath, and 

 in six longitudinal rows, three on each side, of smaller groups on the body. 

 The intervals between these small groups on the body are equal in extent to 

 the intervals between the larger organs with pigment sheath, and the 

 former alternate with the latter. 



The radiating organs with pigment sheath have a silvery lustre. Those 

 of the body measure about 300 ^u in diameter; the suborbitals are larger. 

 There are on each side 1 suborbital (Plate 8, Fig. 41 so), 13 branchiostegal, 

 10 guttural (Fig. 42 g), 25 ventro thoracic (Figs. 41, 42 vt), 20 ventromedial 

 (Figs. 41, 42 ve), 35 ventroanal (Figs. 41, 42 a), 25 anterior lateral (Fig. 41 

 al), 20 medial lateral (Fig. 41 ml), and 35 posterior lateral (Fig. 41 pi), 

 radiating organs with pigment sheath. 



The small organs without pigment sheath are spherical, enclosed in a 

 connective-tissue capsule, and composed of radially arranged cells, which 

 usually enclose a central cavity. 



The organs with pigment sheath closely resemble the compound organs 

 of CJiauliodus harhatus described above. The suborbital organs are so dis- 

 posed as to throw their radiation into the field of vision ; the organs of the 

 body are directed downward. 



Stomias hexagonatus Garman. 



Plate lO, Figs. 47-51. 



This species has been described by Garman ('99, pp. 276, 277, Plate 56, 

 Fig. 5). It possesses five different kinds of radiating organs. An organ in 

 the barbel, a pair of suborbital organs, and on the body simple organs 

 without pigment sheath, simple organs with pigment sheath, and compound 

 organs with pigment sheath. 



The radiating organ in the barbel (Plate 10, Figs. 47, 48, 50), lies in a 

 thickening 1.5 mm. long at the end of the barbel (Fig. 47, 48 L). From 

 its distal part three short terminal threads arise. The radiating organ itself 

 (Plate 10, Fig. 50), is oval and placed transversely in the swelling of the 

 barbel, the long axes of the two crossing nearly at right angles. It is 

 enclosed in a stout connective-tissue sheath (Plate 10, Fig. 50 c), and com- 

 posed of two parts, an upper, dorsal, smaller, dorsoventrally compressed (A), 

 and a lower, ventral, spherical part (B). The smaller upper part is enclosed 

 in a somewhat loose pigment sheath (p), lying within the upper part of the 



