the hollow-headed fishes as well as many
siluroids and some of the loaches. This
method of respiration appears to be a wise
provision of nature to enable the fish,
during periodic dry seasons, to migrate
from pond to pond in search of water in
which their natural food still exists. In
experiments he made with the climbing
perch at Cochin, he found that they would
live without moisture for twenty-four
hours, or even longer; while in Calcutta
the fishermen keep them alive and well for
four or five days, in earthen pots without
water.

Dr. Day has collected a number of
instances of the migration of fishes by land
from one piece of water to another. Mr.
Morris, the Government agent at
Triricomalee, in a letter to Sir Emerson Tennent,
states that as the tanks dry up, the fishes
congregate in the little pools in which
only some thick mud is left; and as the
moisture further evaporates, they crawl
away in hundreds in every direction in
search of fresh water. He has seen them
at a distance of sixty yards from the tanks,
still struggling onward over the cracks
and indentations of dried mud. Sir John
Bowring states that in Siam he saw "fishes
leaving the river Meinam, gliding over the
wet banks, and losing themselves amongst
the trees in the jungles." He also states,
on the authority of Bishop Pallegoix, that
some of these ''travelling fishes" can
wander more than a league from the water.
We have the undoubted evidence of many
Europeans that the climbing perch can
travel by land, at all events, for short
distances, such migrations usually occurring
in the early morning, when the dew is on
the ground. Mr. E. L. Layard once met
a number of perch-like fishes, probably the
anabas, travelling along a hot and dusty
gravel road at midday.

It is not only in India and Ceylon
that fishes exhibit these migratory tendencies.
In many parts of Europe, including England,
eels have been known to travel considerable
distances from ponds to rivers,
and vice versâ. In the West Indies the
flat-headed hassar (doras bancockii) may
be seen marching in large droves,
sometimes during the whole night, from dried-up
tanks to pools of water. Humboldt
saw another species of doras (d. crocodili)
leaping over the dry ground, supported by
its pectoral fins; and he was told of another
specimen that had climbed a hillock some
twenty feet in height.

Dr. Day discusses at considerable length
a very curious subject which has never
been clearly explained, namely, the sudden
appearance, in various parts of India, of
large healthy adult fishes, with others of
proportional sizes, immediately after a heavy
fall of rain, in situations which have been
perfectly dry and hard for months. After
showing the fallacy of Yarrell's theory of
the sudden vivification of ova by the rain,
he points out the almost certainty of the
phenomenon being due to the æstivation of
the fishes during the dry season—a process
closely analogous to the hybernation of
many animals. The low organisation of
many genera of fishes would predispose
them to a state of torpidity, such as is
known to occur in the dry season in other
animals, as the lepidosiren, certain
crocodiles, &c. That many of them are capable
of burrowing, is easily seen by watching
their proceedings in an aquarium, where,
if the water be disturbed, or if they be otherwise
alarmed, certain loaches and various
other fishes dive at once, and totally
disappear by burying themselves in the sand.
The pectoral fins are the agents the fishes
employ in this process. That they actually
do burrow, is incontestably proved by
numerous observations. The callichthys aspar
has been found where wells were sunk
in certain parts of the West Indies. An
anabas was obtained by Sir Emerson
Tennent that had been dug out of a
dried-up tank, a foot and a half below the
surface; and he was informed by a gentleman
of undoubted veracity, Mr. Whiting,
that he had been twice present when the
villagers were engaged in digging up
fishes. He described the ground as firm
and hard, and the fishes as being full-grown
(about a foot long) and jumping on
the bank when exposed to the light.

When Dr. Day was engaged in the
composition of the article from which we have
been drawing our present materials, the
scientific world had heard nothing of a
remarkable mud-fish which is found in
New Zealand. In the autumn of 1867, Dr.
Günther, the well-known author of The
Catalogue of Fishes in the British
Museum, received a letter from Dr. Hector,
the Government geologist in New Zealand,
giving a sketch of a fish five and a half
inches long, which was found at a depth of
four feet from the surface, in a stiff clay
imbedding roots of trees. The locality is
thirty-seven feet above the level of the
Hokitika river, and three miles from the
sea, and had at one time been a back-water
of the river, during floods. Little more