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198 THE RADIATING ORGANS OF THE DEEP SEA FISHES. 
one should say that the radiation — supposing that a radiation is really 
emitted from it—Jis produced by the nerve branches themselves and that 
the paratagential cells are merely packing. 
These organs of Bassozetus resemble the basal part of the radiating discs 
of Halosaurus to be described below and so one might suppose that the 
superficial layer of cylindrical cells there present also occurs here but has 
been lost post mortem. It must however be remarked that no trace of a 
previous presence of such a cell layer could be made out in transverse sec- 
tions of the radiating discs of Bassozelus nasus, 
Leucicorus lusciosus Garman. 
Plate 3, Figs. 10-13. 
This species has been described by Garman (’99, pp. 148, 361, Plates 38, 74, 
Fig. 1). After removing the semitransparent skin of the head the radiating 
discs underlying it. are exposed to view. They appear as roundish white 
spots 1.5-3 mm. in diameter overlying the bones of the skull. They are 
remarkably hygroscopic. If one places one of the discs preserved in alcohol 
in water it rapidly increases in size and swells to the bulk of a pea. On 
each side of the head there are 3 maxillary, 4 orbital, 2 ethmoidal, 3 fron- 
tal, 7 occipitoparietal, 4 mandibular, and 5 opercular radiating discs. 
These organs are similar to, but in their finer structure more highly 
differentiated than, those of Bassozetus nasus described above. <A very stout 
nerve (Plate 3, Figs. 11, 12 n) enters the disc from the side and extends, as 
in Bassozetus, to its centre without decreasing in thickness. Besides this 
main disc nerve there are other smaller nerves (Figs. 11-13 n’), which 
enter the disc in a similar manner. In some cases it appeared as if the latter 
connected different discs with each other. Numerous large blood vessels 
(Figs. 11-13 b) are met with. These chiefly extend from two opposite 
sides towards the centre of the organ and here, bending abruptly at nearly 
right angles, and ramifying, form a vascular ring of rhomboidal shape. From 
this ring numerous branches are given off towards the interior which supply 
the central part of the disc. These blood vessels form a dense superficial 
reticulation (Fig. 13). 2 
The large main dise nerve extends through the basal part of the disc and 
terminates in the centre of the rhomboidal space surrounded by the blood- 
vessel ring. Here it abruptly divides into numerous branches all diverging 
pg 
