MAY 23, 1884.] 
almost 3,000 metres. Thus a fish showing the same 
organic structure is capable of living under pressures 
varying from a half-ton to one and two tons, and 
even more. It may be asked how it is that there are 
forms characteristic of certain depths; for, with zones 
of distribution of so great extent, it would seem that 
abyssal faunas should remain the same. The expla- 
nation of this singular fact is, that fishes which are 
found at a depth of from 600 to 3,600 metres do not 
dwell continuously in the same locality: they are 
travellers, rising and descending in turns into the 
abysses of the sea; and, when they make these jour- 
neys, they go slowly, so that they can endure the slow 
expansion and contraction. I will notice a few spe- 
cies which have made known to us these wonderful 
voyages. We found Alepocephalus rostratus between 
868 and 8,650 metres, Scopelus maderensis between 
1,090 and 3,655 metres, Lepioderma macrops between 
1,153 and 3,655 metres, Macrurus affinis between 590 
and 2,220 metres; the depth of distribution for these 
four species varying by 2,782, 2,561, 2,502, and 2,000 
metres. JI could mention other cases, but those cited 
will suffice to show that the organization of fishes of 
certain depths is such that it is capable of sustaining 
enormous weights without suffering. The structures 
of the fishes just mentioned have nothing special 
which attracts attention, and distinguishes them from 
fishes living near the surface. Their teeth are well 
SCIENCE. 
625 
developed, this peculiarity showing that they are car- 
nivorous (fig. 1). All fishes which live continuously 
at a depth greater than 600 metres are carnivorous. 
This results from the fact, that, with the absence of 
light, vegetation quickly disappears at the bottom, 
and consequently all the species which do not rise to 
within 150 metres of the surface, the point where the 
last Algae are found, are obliged to hunt for food. 
Fig. 2 shows a cut of one of these fishes, Macrurus 
globiceps, whose depth of distribution is between 
1,400 and 3,000 metres. 
If the fishes which transiently visit great depths 
do not show peculiarities in form, this is not the case 
with those which continuously inhabit deep waters. 
This ought not to surprise us, for the structure of 
these animals must suffer important modifications 
before being adapted to these peculiar conditions of 
life. Various influences act upon these fishes. Light 
and vegetation are wanting. Beyond a certain depth 
the temperature of the surrounding water tends to 
become equalized, and the water in which they live 
is always calm. The modifications due to these cir- 
cumstances affect the structure of the tissues, the 
size of the eyes, the development of the sense of 
touch, and the color. Moreover, these fishes possess 
organs which ordinary fishes do not possess. Their 
function is to emit phosphorescent light, and thus to 
supply the light which is lacking. 
Fig. 2. — MACRURUS GLOBICEPS. 
