GENERAL DISCUSSION. 15 
ing brown spots, the whole fading rapidly in alcohol; the allied species, J/. 
spinulosa, from 511 fathoms, Plate XXI., has retained the spots, marks of an- 
cestry and of recent differentiation, but has become blacker and has lost the 
yellow and the white vermiculations; and J. spinosa, Pl. XXII. from 
depths of 1020 to 1270 fathoms lacks all spots and is uniform blackish. 
The pale greenish to yellowish or to bluish assimilative tint, seen on most of 
the colored plates herewith, is decidedly fugitive and disappears soon after 
death of the specimen, or after application of the preserving liquids; in 
many if not most instances it appears to be little more than the luminosity 
affecting the great majority of abyssal creatures. For instances see the 
sharks Isistius, Centroscyllium, and Chlamydoselachus, or the fishes 
Caulolepis, Dicrolene, Macrurus, and others. The occultative luminosity is 
generally distributed over the body and is to be distinguished from the 
monstrative light seen in the lanterns, flashlights, reflectors, lures, ete., of 
particular genera. The latter is a light pertaining to specialized organs of 
various species, is of a variety of tints, and serves on some fishes as means 
of recognition by kindred and on others to decoy and bring the prey within 
reach. The Scopeloids furnish good examples of the recognition marks 
(signa), and in the Pediculates instances are to be seen of a great variety of 
the lures (illicia). As is necessary for its discovery in the light in which it 
is used, the monstrative light is much the stronger; it varies in colors ac- 
cording to the genus or the species on which it is developed; and when in 
function is more or less completely under the control of the individual in 
respect.to appearance, disappearance and brilliancy. The structure of the 
different monstrative organs on a number of the species has been well 
worked out by Lendenfeld in Giinther’s report on the deep sea fishes of 
the “Challenger Expedition.” Creatures living in the ooze in many cases 
are of an intense black in which no luminosity can positively be asserted 
to exist; on such of these as are possessed of lures the latter are most 
often directed upward as if to capture a prey swimming above them, 
for instance Dolopichthys of Plate XTH. Many of the Stomiatoids and 
the Murznoids also are of the same deep black; it would appear as if 
the former inhabited the lower edge of the dark or azoic zone, their lures 
are extended downward as if to secure prey approaching from below. 
The condition of the eyes of deep sea fishes is important evidence in sup- 
port of the theory of an abysmal light; it also tends to establish the idea 
that this light in comparison with that of the sun is very weak indeed. 
