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THE RADIATING ORGANS OF THE DEEP SEA FISHES. 183 
This tissue is rich in blood vessels, The radiating organ proper, that is, the 
mass of cells (pe) which probably emit the radiation, lies in the middle of 
this connective tissue. It is pear-shaped, the thinner end extending outward 
and downward. The cells composing it are flattened and extend parallel to 
the surface of the body. The protoplasm is quite transparent and each cell 
contains a large granular nucleus. The blood vessels form a fine-meshed 
capillary network (b) on the surface of this cell mass, but do not penetrate 
into its interior. 
Radiating organs of this kind seem to be rare in fishes. Somewhat simi- 
lar ones have been described by Emery (’84, p. 473) from the ventral series 
of Scopelus elongatus. 
Chauliodus barbatus Garman. 
Plate 8, Figs. 38-40; Plate 9, Figs. 43-46. 
This species has been described by Garman (’99, p. 271, Plate K, Figs. 2, 
2a). The radiating organs are very numerous. Three different kinds of 
them can be distinguished. The differences between these are considerable 
and clearly discernible with the naked eye. Some of the organs are simple, 
some composed, as in the fishes described above, of an inner spherical and an 
outer paraboloidal part. The simple ones again are either uncovered or 
provided with a pigment sheath. I have designated these three kinds of 
organs accordingly as simple organs without pigment sheath, simple organs 
with pigment sheath, and compound organs with pigment sheath. 
The simple radiating organs without pigment sheath appear as very 
small whitish dots. They are arranged in groups of from 4 to 16. These 
groups are scattered over the medial part of the ventral surface (Plate 8, 
Fig. 39 u) and also occur in great numbers on other parts of the surface, 
chiefly on the back of the fish. 
The simple organs with pigment sheath appear as dark spots 300 p in 
diameter, They are scattered in great numbers over the whole of the sur- 
face and seem to be most numerous on the sides of the head just behind the 
eyes (Plate 8, Fig. 38 x). In the barbel there are 8 of these organs 
(Plate 8, Figs, 38-40 Ba). 
The compound organs with pigment sheath are lustrous, elongated, 
Of these organs there are on each side lL 
o 
about 1mm. long and 600 y broad. 
anteorbital (Plate 8, Fig. 38 ao), 1 suborbital (Fig. 38 so), 18 branchio- 
