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T is merely the object of this brief essay to call attention to

the fact that has on so many occasions been so vividly presented to me, during the course of my dissections of bodies of birds and the preparation of their skeletons, of really how comparatively few of them there are that can boast of being perfectly free and exempt from any form of disease or the sequelæ of disease; and not to make any attempt to classify or write any extended description of those diseases and injuries to which birds are subject. One among the first cases that was brought to my notice occurred some fifteen years ago, while on a collecting tour in the State of Connecticut, at a period before I could lay barely any claim to the knowledge of disease or make any use of what I observed. In passing through the woods on that occasion I picked up from the ground a nearly full grown female Molothrus pecoris, that could barely hop along aud was totally unable to fly. She was extremely emaciated and ill-nourished. My curiosity as to the cause of her disability was soon satisfied when I began to part the feathers to search for some injury that perhaps she had sustained. My first anticipations were quickly dispelled, for instead of any injury, I discovered the integument in various localities, particularly the wings and breast, raised up in rather a tent-like manner, in some eighteen or twenty places. Each of these little pockets was occupied by a yellowish-white larva as large as an ordinary white garden bean. These I easily removed, one by one, with a piece of straw, and carried my bird, apparently now much relieved to the nearest water, some little distance, where she drank as if she had never beheld that fluid before. My surprise now was not very great when, upon releasing her, I found that she could fly some little distance, and undoubtedly subsequently entirely recovered. As I have never seen a similar case, I am to this day ignorant of the habits or even the name of the parasite.

Another remarkable, although common, case of parasitism occurs in Spheotyto, our burrowing owl of the plains. The best example of this I saw in one of these birds two or three years ago. This specimen, too, I could actually pick up from the en

trance of the prairie-dog burrow, where he sat, scarcely caring, apparently, whether he lived or died. Upon removing, when in my study, the skin of this owl, I was not a little astonished to find many of the organs absolutely displaced by "wads” as large, in some instances, as an almond, of a long hair-like worm, of a pale yellow color, the longest being about 6 c.c. in length. Collections of them in the orbits forced the eyes outwards in this case, and a large roll of them occupied the upper third of the tracheo-csophageal interspace, completely wedging the two tubes apart.

Subsequently when the skinless cadaver was thrown aside upon my table, these parasites reared for half their lengths and waved to and fro, lending to the body an appearance as if some kind of a pale colored moss was growing from it.

Exostoses not unfrequently occur, either on the shafts of some of the long bones, or upon the surfaces of the flat ones. I have before me a very pretty specimen where one of these bony outgrowths occupies the angle of the carina in the sternum of a specimen of Eremophila alpestris. It is nearly as large as a pea, and has a lobulated appearance, jutting forwards.

Aneurismal tumors are sometimes to be seen; the sacs have the appearance of having existed for some space of time-in a few instances.

Muscular atrophy, as far as my observations go, is of rather rare occurrence, although I have seen one good example in the muscles of the lower extremities of a specimen of Sturnella magna. There was no apparent cause for it upon post mortem, The bird was very loath to take wing, and was killed on the ground, where his locomotion seemed good.

The results of injuries and gun-shot wounds present many examples of interest, and objects for study, if anything, still more engaging. A few days ago I secured a female specimen of Circus cyaneus var. hudsonius, the horny integuments of whose feet were the sites of many warty excrescences, having the color and general appearances of the parts they occupied. These bodies ranged in size from a duck shot to a small hazel nut. My diagnosis was materially assisted in this case by finding a cactus thorn protruding a little beyond the surface of one or two of the warts, and this foreign body formed the nucleus of all of them.

They were undoubtedly driven forcibly into the feet of this bird, when it seized small mammals among the cactus beds, where they usually burrow for protection. One of the best unions, after gun-shot fracture, I ever had the pleasure of examining (the specimen is now in the Army Medical Museum), occurred, in the upper third of the humerus, in a specimen of Mergus serrator, that I secured several months ago. Taking into consideration the fact that this bird is a vigorous diver, and one os no mean powers of flight, the result, if we may so call it, was an excellent one-there being scarcely any deformity-and the member was as serviceable as ever.

I have seen and possess specimens of many other interesting cases, but their description would extend this paper far beyond the limits. The best examples, and those perhaps worthy at least of a mention, consist of a case of non-union in the palatines of Anas boschus, a depressed fracture in the cranium of Corvus americanus, gunshot injuries resulting in recovery of the brain in Spheotyto and others.

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, of the locust, and to learn something of its general intelligence as an insect and as compared with other insects, it is necessary for us to study with a good deal of care, the organ of the locust's mind, i.e., its nervous system, comprising its nervous centers and the nerves arising from them.

The Nervous System in General.—The nervous system of the locust consists of a series of nerve centers or ganglia, connected by nervous cords called commissures. There are ten of these ganglia in the locust, i. e., two in the head, the first and largest of which is called the brain;" three ganglia in the thorax, and five in the hind-body or abdomen. The brain is situated in the upper part of the head, resting upon the gullet or æsophagus, whence its true name supraæsophageal ganglion. (Plate i, Fig. 1.) The succeeding nerve-center is situated in the lower part of the head, behind the mouth and under the esophagus, hence it is called the subæsophageal ganglion. (Plate 1, Fig. 5.) The brain really is a double ganglion, being composed of two hemispheres, each hemisphere being a single ganglion or nerve-center; all the succeeding ganglia are also double ganglia ; but for convenience we will call the “brain," and each of the succeeding nervecenters a ganglion. Each side of the brain contracts, and then swells out into a rounded portion next to the eye, called the optic ganglion. (Pl. I, Fig. 1.) From this optic ganglion the optic fibers proceed to the facets of the eye. The optic ganglion connects with the train by the large optic nerve. There are, then, two optic nerves, besides three slender nerves (ocellar nerves) sent to each of the three occlli or simple eyes; moreover, a nerve is sent to each of the antennæ, and are hence called the antennal nerves. The relations of the brain to the head, and to the succeeding ganglion, and the origins of the nerves distributed to the eyes, antennæ and ocelli, as well as of the nerves sent to the jaws, etc., are clearly seen in the figures on Plate 1.

1 Adapted for the NATURALIST from the Second Report of the U. S. Entomological Commission, 1880. We are indebted to the Commission for permission to have an edition of five plates struck off from the lithographic stones at the expense of the publishers.

On the other hand the mouth parts, i. e., the jaws (mandibles) and accessory jaws (first and second maxilla, the latter called the labium or under lip) are each supplied by a pair of nerves, called respectively the mandibular, maxillary and labial nerves. These three pairs of nerves arise from the subæsophageal ganglion. (See Pl. i, Fig. 2, g?.)

The Brain of Insects as distinguished from the Brain of Vertebrates.—The “brain," or supraesophageal ganglion is, as we shall see, a much more complicated organ than any of the succeeding ganglia, having important parts which are wanting in all the others, hence it is par excellence nearer to our idea of a brain than any of the other nervous centers. It should be remembered, however, that the word, "brain” is applied to this compound ganglion simply by courtesy and as a matter of convenience, as it does not correspond to the brain of a vertebrate animal, the brain of the horse or man being composed of several distinct pairs of ganglia. Moreover, the brain and nervous cord of the fish or man are fundamentally different, or not homologous with those of the lower or invertebrate animals, though the nervous system of the insects and Crustacea present greater analogies to that of the vertebrates than any other of the lower animals, with the exception, perhaps, of the cuttlefish. The nervous cord of

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