Chapter IV: Treatment of the Skins of Small Mammals

Many hundred beautiful and curious quadrupeds are shot every year and allowed to perish utterly for lack of the little knowledge and skill which would enable the hunter to remove and preserve their skins. The operation is simple and easy, the requirement in tools and materials quite insignificant, and the operator has only to exercise a little patient industry to achieve good results. There are few circumstances under which a determined individual finds himself thwarted in his desire to remove and preserve the skin of a dead animal. In nineteen cases out of twenty the result hinges on his own disposition. If he is lazy, a thousand things can hinder his purpose; if he is determined, nothing can. A sharp pocket-knife, a little powdered alum and arsenic in equal parts, or failing that, common salt alone, will do the business in lieu of a better outfit, for any small mammal that ever lived.

I begin with small mammals, because it is squirrels, rabbits, cats, woodchucks, weasels, opossums, raccoons, and foxes that the beginner will fall in with long before he is called upon to wrestle with such subjects as deer, bear, elk, or buffalo. These general directions apply to the skinning of all terrestrial quadrupeds up to the size of a setter dog, and the preservation of their skins in a mountable condition.

MEASUREMENTS.--The following are the most valuable measurements to take of a small mammal.

1. _Length, from end of nose to root of tail._ This is to be taken with the head stretched out straight as far as it will go. Measure from the tip end of the nose to the point where the tail joins the body. In my judgment it is always best in determining this latter point to take the angle made by the tail (underneath) and the rump when the tail hangs or is bent down at an angle of forty-five degrees to the spinal column. This point is always fixed and constant, and can be quickly and accurately determined by bending the tail down and sticking a pin or awl at the angle. To measure an animal like a monkey on the top of the tail is to attempt the location of a point which can rarely be determined twice alike. For this reason I have always taken this measurement in both large and small mammals underneath the tail.

2. _Length of tail, from root to end of vertebræ._

3. _Length of hind foot._ Bend the heel at a right angle, and measure from the outer extremity of the angle to the tip end of the longest toe, including the nail.

4. _Height at shoulders_, if the animal be not too small. To take this, lay the animal on its right side, then, as nearly as you can, place the right leg and foot in the position they would assume if the animal were standing erect (the sole of the foot must be parallel to the axis of the body), and measure in a straight line from the bottom of the heel to the top of the shoulders. Record, also,

5. _The color of the eyes, and the other soft parts._

6. _Weight, in certain cases._

Do not forget what has been said in Chapter III. about outlines and sketches. On one corner of the outline-sheet we record the name of the specimen, locality, date, sex, measurements, color of eyes, lips, feet, etc. It takes but a few moments' time, and the result is a complete and accurate record of what the animal was in the flesh. These sheets are numbered and filed away, the skin is numbered and put in the bath, and even though it be not until five years later that we are ready to mount it, we can tell as accurately what the animal was like as if it had been received only the previous day. If the specimen is a baboon, for example, with several colors on its face, it was for years my practice to make a rough sketch of the face and put upon it the various colors that belong there, in oil-colors, usually, though sometimes with water-colors. It was also my custom to spend half an hour or so in taking a mould, and making a quick cast in plaster Paris of the face of every monkey or baboon which came to me, unless I already had one which would answer as a model to copy in finishing the face.

SKINNING SMALL QUADRUPEDS.--Lay the animal flat upon its back, head to your right. Hold your knife with the edge up, and push the point through the skin of the throat, precisely in the middle of the neck. Now push the point of the knife forward under the skin, between it and the flesh, and divide the skin in a straight, clean cut along the middle of the neck, breast, and body, quite to the base of the tail. If the animal has a large, fleshy tail, like a dog or raccoon, it must be slit open along the under side (without cutting the hair) for its entire length, except an inch or two at the base. If the tail is small, slender, or bony, like that of a squirrel or a rat, it can usually be slipped out of the skin by pulling the bony part between two sticks held close together against the skin of the tail.

The sole of each foot must be slit open, lengthwise, from the base of the middle toe straight back to the heel, and in case the foot is large and fleshy, like that of a dog, the cut must be continued on up the leg, perhaps one-third of the way to the knee, to enable the skin of the leg to be turned wrong side out over the foot.

Having made all the opening cuts, begin at the abdomen, catch one edge of the skin between thumb and finger, and with the knife cut it neatly and cleanly from the body, leaving as little flesh as possible adhering to the skin. In using the knife do not go at it in a daintily finical way, as if you were picking birdshot out of the leg of a dear friend; for, if you do, it will take you forever to skin your first specimen, and there will be no time left for another. Learn to work briskly but carefully, and by and by you will be able to take off a skin with a degree of neatness and rapidity that will astonish the natives. It is not a dissecting touch that is called for in taking off a skin, but a firm, sweeping, _shaving_ stroke instead, applied to the inside of the skin, and not to the carcass. This applies to all skinning operations on all vertebrates except birds.

After starting at the abdomen, we come very soon to where the foreleg joins the body at the shoulder, and the hind leg at the hip. Disjoint each there, and cut through the muscles until each leg is severed from the body. Skin each leg by turning the skin wrong side out over the foot quite down to the toes. That done, cut the flesh away from the bones of the leg and foot, neatly and thoroughly.

_Never leave the foot of an animal unskinned_, unless it happens to be a very small one, like a chipmunk, or smaller, and the proper way is to skin the flesh out, even then.

Be careful to leave all the bones of each leg attached to each other by their ligaments at the joints (see left hind leg in Fig. 2), and to the skin itself at the toes. _Never throw away the leg bones_, unless the skin you are preserving is to be kept as a pelt or a rug.

Detach the skin from the back, shoulders, and neck, and when you come to the ears, cut them off close down to the head. Turn the skin wrong side out over the head, until you come to the eyes. Now be careful or you will do mischief. Work slowly with the knife, keeping close to the edge of the bony orbit, until you see, through a thin membrane under your knife edge, the dark portion of the eyeball--iris and pupil. You may now cut fearlessly through this membrane and expose the eye. If your work has been properly done, you have not cut the eyelids anywhere. If you are ever in doubt when operating on the eye, thrust the tip of one finger fairly into the eye and against the ball, from without, and cut against it. This is always an excellent plan in skinning large mammals.

Skin down to the end of the nose, cut through the cartilage close to the bone, and cut on down to where the upper lip joins the gum. Cut both lips away from the skull, close to the bone, all the way around the mouth. The lips are thick and fleshy, and must be split open from the inside and flattened out so that the flesh in them can be pared off. Do not mutilate the lips by cutting them away at the edge of the hair, but leave the inside skin, so that in mounting you can fold it in (with a little clay replacing the flesh) and thus make a mouth anatomically correct. Do not shave off the roots of the whiskers, or they will fall out. Gash the flesh between them (they are set in rows), but leave the follicles themselves untouched. Pare away the membrane which adheres to the inside of the eyelids, and turn the ear wrong side out at the base, in order to cut away the flesh around it. If the ears have hair upon them, they must be skinned up from the inside and turned wrong side out quite to the tip, in order to separate the outside skin, which holds the hair, from the cartilage which supports the ear.

For a full description of ear skinning, see another chapter.

The great principle which is the foundation of all valuable field work on mammal skins is this: _A skin must be so taken off, cleaned of flesh, and preserved that the preservative powder or fluid can act directly upon the roots of the hair from the inner side of the skin, and over every portion of its surface._ Neither alum, nor salt, nor alcohol (unless it be of great strength) can strike through a thick layer of flesh and penetrate through the skin to the epidermis quickly enough to save it from decomposition. The epidermis of most animals is of such a close and oily nature that preservatives cannot strike through it from without, and therefore when a skin is removed it must be cleaned of flesh and fat, so that the preservative liquid or dry powder can come immediately in contact with the cutis.

The skin is now off. If the lips have been opened out, the ears skinned to the tip (if they be haired), and the feet well skinned down, we are ready to go on. But first we must clean the skull. Cut the flesh all off, or the most of it at least, for it is not possible to get it all away at the base; cut out the eyes and tongue, and with your brain-hook, or a piece of wire hammered flat at the end and bent up at a right angle, patiently draw out the brain through the occipital opening at the base of the skull. By this time, perhaps, the skin will be bloody in places, or possibly it was dirty to start with. Now is the time to wash it thoroughly in clear water. Remember that a skin which has been dried with blood upon it is damaged forever. It stains the hair, and very often forms a hard, gummy mass which nothing will dissolve.

PRESERVATION OF THE SKIN.--The next step depends upon what you propose to do with the skin, or it may depend upon the conditions under which you are collecting. 1. If you are in your laboratory preparing skins to mount, preserve them all (except quite young specimens and certain others) in a soft, or wet state, in a salt-and-alum bath. 2. If you are in the field (especially the tropics), making a large collection of mammal skins for mounting, by all means do the same if possible. 3. If the skins are for purposes of study _as skins_, during which frequent handling and examination is absolutely necessary, make them up as dry skins. 4. If you lack facilities for preserving them wet, then make dry skins of them. 5. If the necessities of travel and transportation make it necessary to reduce the weight to the lowest possible limit, and to divide it up for carriage overland, make up all skins dry, both little and big. 6. If you have only one or two skins to preserve, it will be less trouble to you to make them up dry at once.

Here are the two methods:

_A._ THE SALT-AND-ALUM BATH.--This is the finest solution ever discovered for the preservation of the skins of quadrupeds that are destined to be mounted. It is inexpensive, simple, and easy to make; its action is perfect; its strength can be regulated to suit any kind of a skin; it never gets stale; and if properly handled will preserve a skin for a hundred years in the same pliable and elastic condition as when it leaves the animal's back. In only two or three instances have I ever known it to change the color of the hair in the least. Every taxidermist knows that it is far easier to mount a fresh specimen in fine style than an old, dry skin which has lost all its elasticity. The work on a soft skin (_i.e._, one which has never been dried) can be done more easily, more quickly, and vastly better. With a dry skin you can make only what it will let you; but with a wet skin you can make just as fine a mount as your skill is capable of producing. And with the latter it makes no difference whether the skin came off the animal last week or ten years ago, except in the case of very young animals. Of these the bath softens the leg bones. For years it has been my custom to preserve all skins that I expect to mount (except the young of the smaller species) in this salt-and-alum bath, and it is almost superfluous to add that I strongly advise all others to do the same. In many ways it is a _great economy_ to do so.

_Directions for Making It._--For every gallon of water put in three-quarters of a pound of alum (one pint) and a pound and three-quarters of salt (about one quart), and heat the liquid to the boiling-point, stirring occasionally, so that the salt and alum will dissolve. Then pour it into a wooden, earthen, or glass vessel, or a tank lined with _lead_ (for zinc or galvanized iron will not answer), and when it is cool, or even milk warm, it is ready for use. Test it with your salometer (which you can procure for fifty cents of Bahmann & Hoehn, 21 Park Place, New York), and see that it stands at 15°. This is the normal strength. If stronger than that, _e.g._, 16° or 17°, the skin will be hardened too much. It can go as low as 13° with safety, but that is the limit. At 12° skins are liable to lose their hair.

_Directions for Use._--If the hair is tight on the skin everywhere, simply immerse it in the bath, leg bones and all, giving it plenty of room at first. Move it up and down, and leave it as much spread out and free from folds as possible. Remember that the fluid must act upon _the inside_ of the skin, for the epidermis is often almost impervious to it. If you allow the skin to lie upon itself in thick folds, stuck together on the inside, those spots are liable to lose their hair in a most unaccountable and aggravating way. If the skin is small and thin, the bath soon does its work; but if it is a large skin, move it up and down, and all about, every day for the first two or three days. By the end of that time its preservation will be complete.

_Half-spoiled Specimens._--Very often a subject will be brought to you in the flesh, several days old, green on the abdomen, and the hair starting to slip off between the hind legs. If the hair pulls out readily on various parts of the body and limbs, it is a gone case; but if it starts only a little on the lower part of the abdomen, and is firm everywhere else, put some bath, with a little extra alum in it, on the fire to get warm, snatch that skin off in a hurry, and without stopping for any fancy touches whisk it into the warm bath. The bath should not be so hot that you cannot bear your hand in it. It will act like magic. Then you can gradually finish your work on the skin, so as to keep it safe from harm. Very often quick work, and a warm bath with plenty of alum in it, will save a skin in fine, mountable shape, when nothing else will. The alum acts as a powerful astringent, drawing together the fibres of the epidermis around the root of each individual hair, and likewise binding together the cutis and epidermis.

_Cleanliness._--You will observe that as fresh skins are put into a bath it gradually loses its strength, and it is also liable to become, in time, so dirty with blood and grease that it must be thrown away. Keep skins that are greasy (bear, seal, etc.) carefully by themselves, and never put the skin of a deer, cat, or any animal with a fine coat in a greasy or dirty bath. If a bath is clean, but of too low strength, make some extra strong bath, say 20°, and add to it and bring it up to 15°. Keep all your bath receptacles tightly closed, or the liquid will evaporate very rapidly.

_Testing the Bath._--If you have no salometer, and are not overparticular, you can test your bath by tasting it; but unless the bath is new and untouched, I prefer the little salometer. By tasting the bath when first made in the proportions given above, and remembering the degree of its astringency upon the tongue, you can make that a standard for comparison--if it suits your taste!

_Skulls and Leg Bones._--The leg bones of all small and medium sized mammals, even up to the deer, can just as well go into the bath, after they have been _thoroughly cleaned of all flesh and tendons_. The skulls, however, had better not go into the solution. Clean them carefully, anoint them all over with thin arsenical soap, put a tag on each to show to what skin it belongs, and let it dry. Don't lay it aside without poisoning, or it will be swarming with dermestes before you know it.

As before stated, a skin must have room while it is curing, but when that has been thoroughly accomplished, which with the largest skins never takes more than four or five days, they can be packed together like sardines so long as the bath is strong enough.

_B._ MAKING DRY SKINS.--_Poisoning and Preserving._--When the skin has been removed and cleaned, the next step is to sew up from the inside any holes that may have been made in the skin by bullets or knives. Then make up a mixture of two-thirds powdered alum and one-third arsenic, and rub as much of it upon the inside of the skin as will stick there. The alum is to preserve the skin, the arsenic to poison it against the attacks of insects. Apply this mixture thoroughly, especially in the feet, ears, head, and tail, for these are the points the dermestes attack first.

_Another Method_, and one which I almost invariably follow when I am compelled to make dry skins, is to anoint the skin with strong arsenical soap,[3]--the finest poison for skins yet discovered,--then rub on the skin, as soon as the soap has been fully absorbed, a mixture of fine salt and powdered alum, in equal proportions. Though the arsenical soap may be thought "mussy" at first, it should not be used thin and watery, but as a thin paste, like thick cream. The advantages of this method are--(1), that the skin is more thoroughly poisoned, especially externally, on the hairless portions; (2), the skin dries without becoming so hard and brittle and inelastic; and (3), it can be softened and mounted much more easily and successfully than skins prepared by the first method. For skins which are to be mounted, the advantages of this method are very obvious.

_The Simplest Method_.--If you have neither arsenic nor arsenical soap, and yet wish to save a skin so it can be sent to a taxidermist in good condition, prepare it with fine salt alone. Use the salt liberally, and if the weather is warm, leave the skin turned wrong side out and roll it up in a quantity of it. If you use it sparingly, the skin will absorb it all in a day or two, literally "cry for more," and failing to get it will sweat and spoil. It is simply a question of enough salt.

Even when collecting in the field, I nearly always cure small skins with salt only, so that they will stay quite soft and fresh until they get to the laboratory, and then go into the bath without ever having been dried.

_Rats._--Skins preserved with salt only must be carefully guarded from the attacks of mice, rats, cats, dogs, and other vermin that go about seeking what they may devour.

MAKING UP A DRY SKIN.--_The Legs._--Having applied the preservatives, if you propose to make up your specimen as a dry skin, wrap a little tow, oakum, cotton, or cotton cloth around the bones of each leg, to partly replace the flesh, and keep the skin away from the bone, so that both can dry quickly. If you have no other material, paper will do. In the East Indies, where transportation was difficult, I used to carry with me bundles of coarse brown paper such as the grocers use, and used it for wrapping the leg bones of monkeys, foxes, and the like. But for the small rodents, one must have either tow, oakum, cotton, or cloth, the preference being in the order named. On no account should the skin be left to dry down upon the bone. The proper filling out of the legs is desirable in order that they may have a neat, shapely, and natural appearance, so that the hair will lie naturally, and can be studied to advantage. If this part of the process is neglected, the skin of the leg shrivels up, dries down upon the bone, and looks like a mummy. In the tropics the moisture in a leg bone is sufficient to cause the decay of the skin which surrounds it unless they are separated by some kind of wrapping. To avoid this, some tropical, collectors allow their skins to dry _wrong side out_, a most lazy and vicious habit, the results of which are in most cases totally worthless.

Having wrapped the leg bones enough fairly to replace the flesh, turn back the skin of the leg until it comes right side out again, adjust the skin neatly, and make the member as shapely and natural as you please.

_The Skull._--There are two ways of disposing of the skull. The universal custom has been to replace it in the head, with a little filling in the cheeks and orbits, the lips neatly adjusted on the teeth, and the eyelids also in their place, half open. This makes the best looking skin, and unless you wish to study the skull, is the best method to follow. For skins that are specially designed for study, the plan lately adopted by the curator of mammals of the National Museum is an excellent one. It is to remove the skull entirely from the head, and in case of all mammals smaller than a coyote, put it in the centre of the body, with the filling, in the line of the seam along the belly, so that by cutting a few stitches in the dry specimen it may be readily taken out at any time. The advantages of this arrangement are obvious.

_The Tail._--The tail must be disposed of according to its character. If it is long and slender, take a small wire, wrap it with tow or cotton cloth, so that the skin cannot touch the iron at any point, insert it in the tail and sew it up with a few long stitches. If you have not the means wherewith to do this, whittle a slender stick to a point, and insert it in the tail from within two inches of the body out to the tip. If the tail is large, and has been split open for its entire length, it can be left flat.

_Filling._--Begin at the head and fill out the head, neck, and body to about the natural size of the animal when alive, _but no larger. Better leave it too small than fill it too full_, and stretch the skin out of proportion. With needle and thread sew up the skin to give it a neat appearance, beginning at the throat. Comb and brush the hair so that it will lie naturally, and show its texture and colors to the best advantage. Take a stitch also in the centre of the lips to hold them together.

_Shaping._--The ends to be sought in laying out a skin to dry are, to have it take up a limited amount of space in a drawer, to have all breakable points protected, and at the same time to have all parts of the specimen accessible for examination. The shape of a dry skin, therefore, must depend upon its character. The handsomest collection of small mammal skins that I have ever seen is that of Dr. C. Hart Merriam, Chief of the Bureau of Economic Ornithology and Mammalogy, Department of Agriculture. Although it is purely a private collection, it contains at this date 5,750 skins. Dr. Merriam's method of shaping a skin is certainly, so far as looks are concerned, the best yet devised. Fig. 4, on the opposite page, shows it perfectly. The tail is wired, and extends straight out behind, lying between the hind legs, which also extend directly backward. The forelegs are drawn forward just far enough apart to allow the head to lie between them. The skin is well shaped, and lies flat upon the belly, with all the members resting down upon the bottom of the drawer.

With specimens having long tails this arrangement is open to one objection. In the rough-and-tumble experiences that collections made in the field almost inevitably go through before they reach safe anchorage in the museum, a long tail sticking straight out for its full length is very liable to suffer damage in various ways, especially at the tip. For this reason I always bend the tail down and lay it along on the belly, with a stitch or two to hold it there, safe from harm (Fig. 5). And with such animals as monkeys, sloths, cats, etc., having long and slender forelegs, I always place those members close alongside the body, instead of extending them their full length toward the front.

STEEL COMBS.--For dressing the hair of an animal it pays to have a furrier's fine steel comb, and a coarser comb of German silver, such as can be obtained at seventy-five and fifty cents each, respectively, of J. Ruszits, No. 73 Mercer Street, New York. The same furrier also furnishes a very large steel robe-comb (like an infant garden rake), which is very useful on large mammals having long, matted hair, such as buffaloes, camels, llamas, and the like.

FOOTNOTE:

[3] See recipe in Chapter XLV.