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At Galway, in the river which runs from Lough Corrib, is a large Salmon fishery. LOUGH CORRIB is upwards of twenty miles in length, and some parts six broad, having many fine islands upon it: near this lake is that of Lough Mask, almost half the breadth of the first, and nearly as long; the former is wholly in the county of Galway, part of the latter in that of Mayo; in both are found the Gillaroo Trout, which is generally from twelve to eighteen, but increases so high as thirty pounds weight; these fish are esteemed for their fine flavour, which is supposed to exceed that of any other Trout; their make is similar to the common, except being thicker in proportion to their length, and of a redder hue both before and after being dressed. The Gillaroo is remarkable for having a gizzard resembling that of a large Fowl or Turkey; it is usual to dress the gizzards only, which are considered as very favourite morsels.
The famous JOHN HUNTER made this curious fish an object of his attention, and an extract from his observations upon it may not improperly here find a place: He states, that "one of the digestive Organs of this Trout being so very extraordinary as to have given name to it, and to be looked upon as its distinguishing characteristic: to throw some light upon the question, whether its resemblance to a gizzard be such as to render the appellation proper, it is expedient to state some general facts. Food of animals may be divided into two kinds; what does require mastication to facilitate digestion, and what does not: all animal food is of this latter
kind; but grain, and many other substances which serve for aliment, require a previous grinding or trituration; and therefore animals which live on such food are provided with organs for that purpose. Such birds as live upon food, to digest which trituration is indispensable, have the power of masticating and digesting united in one part, the gizzard, which is for that end peculiarly constructed. In granivorous Birds, therefore, a single organ answers both to the teeth and stomach of granivorous Quadrupeds, (who have two powers distinct from each other, to masticate and digest their food; the first being executed by teeth of a particular form, which serve as so many grindstones, for reducing their food to powder, before it is conveyed into the stomach for digestion,) and consequently the gizzard alone of Birds will point out the food of the species as clearly as the teeth and stomach together do in those Animals in which the two offices of mas. tication and digestion are not joined together in the same part.
"As it appears then to be the difference of the stomachs only that fits birds for their different kinds of food, it is evident that every gradation of stomach must be found among them from the true gizzard, which is one extreme, to the mere membraneous stomach, which is the other; since the food of the various species is from the hardest grain to the softest animal matter. The two extremes above-mentioned are easily defined, but they run so into each other that the end of one and beginning of the other are quite imperceptible: similar gradations are observed
in the food, the kinds suited to the two extremes, mixing together in different proportions, adapted to the intermediate states of stomach.
"A true gizzard is composed of two strong muscles placed opposite, and acting upon each other, as two broad grindstones. These muscles are united at their sides by a middle tendon, into which the muscular fibres are inserted, and which forms the narrow anterior and posterior sides of the flat quadrangular cavity, wherein the grinding is performed: the upper end of this cavity is filled up by the termination of the œsophagus, and the beginning of the intestine; the lower end consists of a thin muscular bag, connecting the edges of the two muscles together. The two flat lateral sides of the grinding cavity are lined with a bony substance, similar to a hard and thick cuticle.
"The two large muscles may be considered as a pair of jaws, whose teeth are taken in occasionally, being small rough stones or pebbles which the animal swallows; and from the feeling on the tongue it can distinguish such of them as are proper from those that are smooth, or otherwise unfit for the purpose, which last it instantly drops out of its mouth. There are other animals which masticate their food in their stomach, but their teeth are by nature placed there: Crabs and Lobsters are thus formed. Some Birds with gizzards have also a Craw or crop, which serves as a reservoir and for softening the grain; but as all of them have not this Organ it is foreign to our present purpose.
"The gradation from gizzard to stomach is made
by the muscular sides becoming weaker and weaker, and the food keeps pace with this change, varying gradually from vegetable to animal; and we find that in granivorous animals of all sorts there is an apparatus for masticating their food, although of various kinds and differently placed." After describing the manner of carnivorous quadrupeds and birds taking and digesting their food, Mr. H. thus proceeds:— "Of all the fish I have seen, the Mullet is the clearest instance of the structure of its stomach approaching to that of birds; its strong muscular stomach being evidently adapted, like the gizzard of birds, to the two offices of mastication and digestion. The stomach of the Gillaroo Trout holds the second place; but still neither of these stomachs can be justly ranked as gizzards, since they want some of the most essential characters; viz. a power and motion fitted for grinding, and the horny cuticle. The stomach of the Gillaroo Trout is, however, more circumscribed than that of most fish, and endued with sufficient strength to break the covering of small shell-fish, which will most probably be best done by having more than one in the stomach at a time, and also by taking large and smooth stones into it, which will answer the purpose of breaking, but not so well that of grinding; nor can this fish's stomach possess scarcely any power of grinding, as the whole cavity is lined with a fine villous coat, and whose external surface every where appears to be digestive, and by no means fitted for mastication.
"The stomach of the English is exactly of the
same species with that of the Gillaroo Trout, but its coat is not so thick by two-thirds: how far this difference in thickness of stomach avails to make a distinct species, or barely a variety of the same, is only to be determined by experiment, which might be tried by putting some Gillaroo Trout, male and female, into water in which there are no Trout, and observing if they continue unaltered.
"The Esophagus in the Trout is considerably longer and smaller than in many other classes of fish. The intestines are similar to those of the Salmon, Herring, Sprat, &c. the pancreas is appendiculated (this name to the pancreas Mr. H. has adopted from its appearance). The teeth shew them to be a fish of prey. So far, therefore, (concludes Mr. HUNTER,) as warranted by analogy, we must not consider the stomach of this fish as a gizzard, but as a true Stomach."
Respecting the Gillaroo Trout Mr. PENNANT has the following remarks:-" The Stomachs of the common Trouts are uncommonly thick and muscular; they feed on the shell-fish of lakes and rivers, as well as on small fish; they likewise take into their stomachs gravel or small stones to assist in comminuting the testaceous parts of their food. The Trouts of certain lakes in Ireland, as those of the county of Galway, and some others, are remarkable for the great thickness of their stomachs, which, from some resemblance to the organs of digestion in birds, have
The English Trout swallows shell-fish, and also pretty large smooth stones, which serve as shell breakers.