264 
gresses with a measured grace of action surpassed 
by no other species of its tribe. In the Picked 
Degfish, Acanthias, the general contour of the body is 
very similar to that of the last species, but the pectorals 
being much smaller, more rapid action of the caudal 
extremity is requisite for supporting it in the water, and to 
this has to be added a great rigidity of the anterior half 
of the vertebral column, causing the fish to swerve from 
side to side with each stroke of the tail, the same cause 
preventing it also from turning corners with ease and 
rapidity, and altogether imparting to it a want of grace of 
action compared with that of other members of its tribe. 
For the foregoing reason this species requires a tank of 
larger size for its preservation in good health than other 
Dogfish, as if confined within the boundaries of a small 
one, it beats its head against the sides and rockwoik to 
such an extent, that the cartilage of the skull is frequently 
exposed toview. Inthe Spotted Dogfish, Scy//e2m, the whole 
body is more elastic even than in A7zs¢elus, a character ad- 
mirably fitting it for its ground-loving habits, and enabling 
it to explore, and adapt itself to every sinuos ty of the 
ground while hunting for its prey. When swimming in 
open water, ic is distinguished by a more rapid action and 
swifter progress than A/wste/us, though at the same time 
the greater amount of force expended in its movements 
deprives it of the peculiar grace associated with that 
species. 
One anomalous form standing as it were between the 
Sharks and Rays, the Monk, or Angel fish, AAzna 
sguatina, affords in its locomotive characters an inte- 
resting link further indicating its close affinity rather 
with the former than the latter group. The habits of this 
fish are essentially nocturnal, and throughout the daytime 
it usually reclines sluggishly at the bottom of its tank, 
Its depressed body and broadly expanded pectoral tins, 
resemble those of a Ray more than a Shark, and like the 
former fish it seeks concealment by burying itself beneath 
the sand or shingle, excavating a hole with the shovel- 
like action of these broad fins, and thus waits in ambush 
for passing prey. Immediately the Monk fish rises above 
the surface of the ground, its true affinities become ap- 
parent, progression being effected entirely by the lateral 
action of the caudal extremity, as in the Sharks, though 
in a more slow and clumsy manner. The lateral position 
of the gill openings in this fish forms its chief shark-like 
anatomical character, and to this has to be added its 
viviparous habits. 
In the Batoidea, or Ray tribe, onward motion is ac- 
complished by a singular, even, and wing-like action of 
the broad pectoral fins, the aitenuated caudal extremity 
remaining perfectly quiescent, and serving only to preserve 
the fishes’ equilibrium. Swimming towards the surface 
of the water, these fish present a most remarkable bird- 
like aspect, their large flapping fins reminding the ob- 
server of the flight of the heron or some other unwieldy 
representative of the Grallian order, while the slender tail 
dependent in the rear suggests the characteristic mode in 
which those birds hold their long legs, while pursuing 
their course through the more subtle medium which they 
inhabit. 
Proceeding to the Teleostean group, we find the means 
by which the same organs are made subservient to the 
faculty of locomotion, still more highly diversified ; space, 
however, will only admit of a few selections. 
In the Gurnards, 77Zg/a, during rapid movement, all the 
fins are pressed closely against the body, the broad wing- 
like pectorals being shut up like a fan, while the fish is 
propelled swiftly through the water by the vigorous undu- 
lations of the tail ; when the fish moves leisurely the pec- 
torals are opened to their full extent, acting as balances, 
In many species, such as the Striated Gurnard, 7. déxeata, 
these fins are brilliantly coloured, reminding the observer, 
especially when regarding them from above, of gorgeous 
ropical butterflies, gliding along with the smooth action 
AS DPA a Sa ne eae 
NATURE - . 
[Fuly 31, 1873 
characteristic of the Vanessa tribe. Yet a third property of 
motion is possessed by these remarkable fish, Settling on 
the ground at the bottom of the water, they are capable of 
literally walking overit by means of the three free rays of 
the pectoral fins, which are situated a little in advance of 
the others, and are curved and especially thickened, to 
adapt them for their anomalous be 
The Gemmeous Dragonet, Callionymus lyra,a small 
and beautiful fish sonewhat resembling the Gurnards in 
outward appearance, is distinguished by an essentially 
different mode of progression. The habits of this species 
are rather sluggish ; it spends much time reclining on the 
ground, occasionally moving for short distances just 
above its surface, by the flitting action of the delicate pec- 
toral fins. Onascending towards the top of the water, its 
swimming capacities are shown to be very limited, being 
restricted to the weak vibrations of the pair of fins above 
mentioned, and which impart to it a peculiar jerky 
action. The male in this species is recognised by 
the extraordinary length of the first ray of the anterior 
dorsal fin, which is raised and depressed at pleasure 
like the latteen sail of a Mediterranean fishing yawl. 
This singular appendage appears, from my own observa- 
tions of the species in connnement, to be subservient to 
the same end as the wattles, crests, and other abnormal 
adjuncts of the male in the Gallinaceous birds—for the 
purpose of fascinating their mates; to this is added a 
similar heightening of the colour, which is carried to such 
an extent in this fish, that the two sexes were long re- 
garded and described as separate species, under the 
respective titles of Cal/ionymus lyra and dracunculus. 
In the Pipe-fish and Sea-Horses, Syugnathus and 
Hippocampus, representatives of the Lophobranchii, the 
organs of locomotion are reduced to their minimum, 
being often restricted, in the former genus, to a single 
median dorsal fin, and being at the most supplemented 
by a pair of diminutive pectorals and a rudimentary 
caudal. In all cases this dorsal fin is the chief propelling 
instiument, and in motion, rapidly undulating from end 
to end, illustrates the action of the Archimedian screw, 
driving the fish through the water on the same principle. 
Dr. J. E. Gray was the first to point out this remarkable 
peculiarity, in the case of Syugnathus, from observing 
these fish in the Aquarium at the Zoological Gardens. 
In both Syngnuathus and Aippocampus the animal 
usually assumes a vertical position while progressing 
through the water. 
The John Dorée, Zeus fader, affords us an example of 
the same principle noticed in the Syngnathidee, applied 
to the purposes of locomotion, though to a still more re- 
markable and extensive degree. 
One of these singular looking fish added to the 
Brighton tanks about two months since, has continued in 
perfect health up to the present time ; and although of 
shy and retiring habits, has already yielded many points 
of interest in connection with its life history. The ordi- 
nary position assumed by this fish is the neighbourhood of 
some projecting rock near the bottom of its tank, and 
against which it sometimes inclines in a leaning posture, 
remaining motionless for hours together. Its ordinary 
progress from place to place is remarkably slow, and it is 
only when on rare occasions it rises high in the water, 
that the beautiful mechanism that guides its movements 
can be appreciated. It may then be seen that the only 
organs calied into action are the narrow and delicate 
membranes of the posterior dorsal and anal fins, each of 
which vibrates in a similar manner to the single dorsal of 
the pipefish ; the lor g filamentous first dors.l, pectorals, 
ventrals, and caudal fins meanwhile remaining perfectly 
motionless. Thus this wary fish, with an almost imper- 
ceptible action, silently and stealthily advances upon its 
intended prey, engulphing it in its cavernous mouth 
almost before the hapless victim is aware of its enemy’s 
approach, W. SAVILLE KENT 
