On account of the extreme variability of the sheep under culture, it is generally supposed that the innumerable domestic breeds have all been derived from the few wild species; but the whole question is involved in obscurity.  According to Darwin, sheep have been domesticated from a very ancient period, the remains of a small breed, differing from any now known, having been found in the famous Swiss lake-dwellings.

Compared with the best-known domestic breeds, we find that our wild species is much larger, and, instead of an all-wool garment, wears a thick over-coat of hair like that of the deer, and an under-covering of fine wool.  The hair, though rather coarse, is comfortably soft and spongy, and lies smooth, as if carefully tended with comb and brush.  The predominant color during most of the year is brownish-gray, varying to bluish-gray in the autumn; the belly and a large, conspicuous patch on the buttocks are white; and the tail, which is very short, like that of a deer, is black, with a yellowish border.  The wool is white, and grows in beautiful spirals down out of sight among the shining hair, like delicate climbing vines among stalks of corn.

The horns of the male are of immense size, measuring in their greater diameter from five to six and a half inches, and from two and a half to three feet in length around the curve.  They are yellowish-white in color, and ridged transversely, like those of the domestic ram.  Their cross-section near the base is somewhat triangular in outline, and flattened toward the tip.  Rising boldly from the top of the head, they curve gently backward and outward, then forward and outward, until about three fourths of a circle is described, and until the flattened, blunt tips are about two feet or two and a half feet apart.  Those of the female are flattened throughout their entire length, are less curved than those of the male, and much smaller, measuring less than a foot along the curve.

A ram and ewe that I obtained near the Modoc lava-beds, to the northeast of Mount Shasta, measured as follows: 

Ram.        Ewe.
ft. in.     ft. in.
Height at shoulders                       3   6       3   0
Girth around shoulders                    3  11       3   3-3/4
Length from nose to root of tail          5  10-1/4   4   3-1/2
Length of ears                            0   4-3/4   0   5
Length of tail                            0   4-1/2   0   4-1/2
Length of horns around curve              2   9       0  11-1/2
Distance across from tip to tip of horns  2   5-1/2
Circumference of horns at base            1   4       0   6

The measurements of a male obtained in the Rocky Mountains by Audubon vary but little as compared with the above.  The weight of his specimen was 344 pounds,[2] which is, perhaps, about an average for full-grown males.  The females are about a third lighter.

Besides these differences in size, color, hair, etc., as noted above, we may observe that the domestic sheep, in a general way, is expressionless, like a dull bundle of something only half alive, while the wild is as elegant and graceful as a deer, every movement manifesting admirable strength and character.  The tame is timid; the wild is bold.  The tame is always more or less ruffled and dirty; while the wild is as smooth and clean as the flowers of his mountain pastures.