PISCES FISHES " To whatever portion of the animal world we turn our attention, we find the lowest and least perfectly organized tribes to be in habitants of the water. To dwell upon land, necessarily demands no inconsiderable share of strength and activity, limbs sufficiently strong to support the weight of the body, muscles possessed of great power and energy of action, acute and vigilant organs of sense, and, moreover, intelligence and cunning proportioned to the dangers and necessities of terrestrial existence.
" The inhabitant of the waters, on the contrary, although less highly gifted, may be fully competent to enjoy the position it is destined to occupy. Being constantly buoyed up on all sides by a dense element, it is easily supported at any required altitude without much muscular effort ; but feeble limbs are re quired to guide its path through the water, and slight impulses suffice to impel it forward.
" The surface of the body of fishes, is in most instances covered by numerous scales, which vary considerably in size and substance in different species. The arrangement of these scales exhibits considerable uniformity. Each scale is attached to the fish by its anterior edge ; and the manner in which the scales overlap each other in different genera, is variable, and gives an appearance of form to each scale which in reality it does not possess. By maceration in water, scales exhibit a series of laminre, the smallest in size having been first produced: they re semble a cone, the apex of which is outward, the smallest being in the centre ; hence the appearance of numerous concentric lines all of the same shape, which mark the growth.
"The fins are important, not only as organs of motion, but as affording by their structure, position, and number, materials for distinguishing orders, families, and genera. The membranes of the fins are thin, and more or less transparent, supported by slender elongated processes of bone, some of which consist of a single piece, which is pointed at the end ; such fin rays are called spinous rays. Others are formed of numerous portions of bone united by articulations, and frequently divided at the end into several filaments ; these, from their pliant nature, are called soft or flexible rays, and two leading divisions in systematic arrange ment are founded on this difference in structure. The number of fin rays in each fin of different examples of the same species, is not always exactly alike. The names given to the different fins are derived from the part of the body to which they are attached.
" The use of the operculum or gill covers, is to close the aper ture behind the gills. The blood in fishes, while passing through the gills or branchim, receives the influence of oxygen from the water which enters by the mouth and goes out by this aperture.
In the fishes included in the first three orders, the gills are so formed, and so freely suspended, that the water bathes in its passage, every part of their surface.
" The branchim, or gills, in fishes possess complex powers, and are capable of receiving the influence of oxygen, not only from that portion of the atmospheric air which is mixed with the water, but also directly from the atmosphere itself.
" The eyes in fishes are observed to occupy very different posi tions in different species. In some they are placed high up, near the top of the head, but more frequently on the flattened side of the head, but always so situated as to best suit the exigencies of the particular fish.
" The sense of hearing has by some been denied to fishes, per haps because they exhibit no external sign of ears, but the Chinese, who breed large quantities of the well known Gold-fish, call them with a whistle to receive their food. Sir Joseph Banks used to collect his fish by sounding a bell ; and Carew, the histo rian of Cornwall, brought his Grey Mullet together to be fed, by making a noise with two sticks.
" But from the rigid nature of the scaly covering of the gene rality of fishes, it is probable they possess but little exter nal sense of touch ; but they are not wholly unprovided with organs which, in the selection of their food, are of essential service. The lips in many species are soft and pulpy ; the mouths of others are provided with barbules or cirri, largely supplied with nerves, 'which are doubtless to them, delicate organs of touch, by which they obtain cognizance of the qualities of those substances with which they come in contact. The Gur nards may be said to be provided with elongated, flexible, delicate fingers, to compensate for their bony lips. It is a rule, almost without exception that I am aware of, that those fishes provided with barbules or cirri about the mouth, obtain their food near the ground ; and these feelers, as they are popularly called, ap pear to be a valuable compensation to those species, which, re stricted by instinctive habits to feeding near the bottom of water that is often both turbid and deep, must experience more or less imperfect vision there from the deficiency of light. The olfactory nerves in fishes are of a very large size, and their sense of smell may be presumed to be acute, from the selection they are known to make in their search after food ; and the advantage said to be gained by the various scented oils with which some anglers impregnate their baits.