THE RADIATING ORGANS OF THE DEEP SEA FISHES. 175 
tion as “ polygonal,” meaning perhaps polyedric. The latter are, as it has been 
described above of A. dychnus, also in A. hemigymnus, smaller than the former. 
Handrick found blood vessels but no nerves in the middle region. The ex- 
tent of the gelatinous tissue occupying the distal part of the cone is dif- 
ferent in the different organs; it is absent altogether in the anteorbitals. 
In° this region a loose network of connective tissue with large nuclei ex- 
tends, the interstices being occupied by a gelatinous substance (’01, p. 58). 
According to this, the latest paper on A. henigymnus, the radiating organs 
_ of this fish seem to have very much the same structure as those of A. dychnus. 
Sternoptyx obscura Garman. 
Plate 6, Figs. 26, 27. 
This species was described by Garman (’99, p. 232, Plate 53, Fig. 1). 
The radiating organs are, as in <Argyropelecus ychnus, very conspicuous. 
There are on each side 2 opercular (Plate 6, Fig. 26 op), 5 branchiostegal 
(br), 10 ventrothoraic (vt), 38 ventral (ve), 3 anterior lateral (al), 3 poste- 
rior lateral (pl), 3 anal (a) and 4 ventrocaudal organs (ve). As in Argyrope- 
lecus lychnus all these groups form rows in which they lie close together. 
The 20 ventrothoracic organs of the two sides are joined to form a medial 
crest protruding from the ventral side of the fish. The inner regions of 
the internal parts of these organs are joined and form a continuous mass. 
The axes of all the organs enclose very small angles with the outer surface 
and thus lie nearly paratangentially. The 2 opercular of each side are 
oblique, directed downwards and backwards, all the others more or less 
vertically downwards, 
Besides these organs observed by me, Garman (’99, p. 233) mentions ¢ 
silvery area below the eye which he thinks may be a rudimentary suborbital 
radiating organ. 
The structure of the organs is apparently the same as in Argyropelecus 
lychuus. In some of them, however, chiefly in the ventrothoracic organs 
(Plate 6, Fig. 27), the proximal part of the pigment sheath (p) is thicker 
and the middle and outer region together are much less extensive than 
in that fish, These appear here (1 and s) as a rather thin, oblique, lenticular 
body separating the extensive gelatinous outer mass (gl) from the cellular 
inner region (g). Traces of stratification could also be detected in the 
outer region. 
Se eS 
