aT 
THE RADIATING ORGANS OF THE DEEP SEA FISHES. 199 
radially in a paratangential plane. In the central part of the lower portion 
of the disc numerous large cavities, which appear empty in sections (Fig. 13 
ev), are observed. At the base of the disc a layer of scattered pigment cells 
(Fig. 13 p) occurs. No particular structures could be made out in the 
tissue forming the dise itself. In transverse sections (Fig. 13) through it 
one sees paratangentially orientated plate-like or spindle-shaped elements, 
probably connective-tissue cells, sections of nerves and blood vessels and 
here and there granular elements which look like nerve cells. 
As in the case of Bassozetus (p. 198), also here in Leucicorus lusciosus the 
possibility of the discs examined being incomplete must be taken into con- 
sideration. If the discs as observed were covered by a layer of cylindrical 
cells these organs of Leucicorus would become very similar to those of Ha- 
losaurus described below. Such a cylinder cell layer may have been 
present on these organs during life; I failed however to find any trace of 
it in the sections. 
Halosaurus radiatus Garman. 
Plate 11, Figs. 52-57. 
This species has been described by Garman (99, pp. 298, 364, Plate 60, 
Figs. 2, 2a, Plate 84, Figs. 3-6). The radiating dises are situated on the 
head and, according to Garman (’99, p. 298, Plate 60, Fig. 2, Plate 34, Figs. 
3-6), also in a longitudinal row on each side of the body. They lie under 
the skin and are spindle-shaped, the long axis being disposed paratangen- 
tially. The largest are 3 mm. long. On each side of the head there are 7 
maxillary, 7 orbital, 8 ethmoidal, 4 occipitoparietal, 4 mandibular, and 9 
opereular radiating discs. ‘Those on the body could not be made out in the 
somewhat injured specimen at my disposal. 
In Halosuwrus radiatus the radiating dises are obviously connected with 
the slime-canal system. They are in fact local differentiations of the walls 
of certain slime canals. The cephalic slime canals in which the organs of 
the head lie, extend as usual paratangentially below the outer skin. These 
slime canals are enclosed in a stout, apparently structureless sheath (Plate 11, 
Fig. 56s). Within this a layer of connective tissue (Figs. 56, 57 c) is met 
with, in which slender, probably spindle-shaped cells arranged paratangen- 
tially can clearly be made out. This connective-tissue layer is stouter on the 
lower side, that is, in the floor, than on the upper side, that is, in the roof of 
