THE RADIATING ORGANS OF THE DEEP SEA FISHES. 191 
C. sloani in detail. To his statements concerning the simple organs we have 
referred above. ‘The compound organs of this fish (01, pp. 14, 16, Fig. 7) 
consist, according to him, as in C. barbatus, of a proximal, nearly exactly 
spherical part, to which a funnel-shaped neck, separated by a distinct 
incision, is attached. In the compound organs of the body the funnel is 
cut off obliquely where it abuts on the surface of the body. In the 
branchiostegal organs transversely. Hach compound organ consists of an 
outer pigment layer, a reflector, a connective-tissue capsule, and a central 
cell mass, in which three regions, an outer, middle, and inner ean be distin- 
guished. These regions correspond to the three regions in the organs of 
C. barbatus. Beyond the outer region gelatinous tissue is met with, occupy- 
ing the space between its outer face and the surface of the fish. The outer 
region is divided by connective-tissue membranes into very narrow facets di- 
verging distally. The middle region is clearly divided into an outer portion, 
occupied by polyedrical cells, and an inner portion divided into radial facets. 
The inner region consists of radially arranged conic cells, the larger central 
parts of which are fine grained and stainable with eosin but not with haema- 
toxylin, whilst the much smaller peripheral portions forming about a quarter 
of the length of each cell are readily stainable with haematoxylin. Each of 
these cells contains one or two nuclei situated in the peripheral portion. 
[t will be seen from this that the structure of these organs in C. s/oani is 
very similar to that in C. barbatus. The chief differences between them are 
the following: in C. sloan’ the facets of the outer region are narrow, the 
middle region is distinctly divided into an outer and an inner portion, and 
the cone cells of the inner region contain one or two nuclei; in C. barbatus, 
on the other hand, the facets of the outer region are broad, the middle 
region is not divided into two clearly distinct parts, and the cone cells of the 
inner region always contain a single nucleus. 
Idiacanthus antrostomus Gilbert. 
Plate 8, Figs. 41, 42. 
This species was first described by Gilbert (’90, p. 54), later more in detail 
It possesses two kinds of radiating organs, one 
The former are exceedingly 
roups (Plate 8, Fig. 41 u) on the 
by Garman (99, p. 280). 
without, the other with, a pigment sheath. 
small and arranged in two large elongate g 
