Most of the lore surrounding unicorns, such as their captivity only at the hands of virgins, etc., is obviously fanciful. Other legendary aspects, such as the grinding of their horns into powder to neutralize poison, probably originated with conmen who carved narwhal tusks for sale to wealthy buyers. But, let's not be distracted from the real issue just because some pagan mythology has been attached to them. If they are or were real, then they were created by God who is worthy of praise (not mockery). None of us would question the existence of cats, for example, just because some people think they have nine lives.
The real issue is: Do or did unicorns exist? If the unicorn of the Bible is in fact the rhinoceros, then there is no problem whatsoever with the KJV. Remember, "unicorn" and "rhinoceros" are synonyms, according to Webster (1828), so we cannot righteously declare that the KJV translators should have chosen one synonym over the other.
Here are some interesting notes on the unicorn that I found in Albert Barnes' Notes on the Bible. Section 8 was most interesting. If you want to see a rendering of what is deposited in the Museum of the London Missionary Society, go to:
http://penelope.uchicago.edu/oddnotes/timbsunicorns.html and scroll to the bottom of the page. Campbell noted that "the animal is considered by naturalists, since the arrival of the skull in London, to be the Unicorn of the ancients, and the same that is described in Job. xxxix."
From Albert Barnes' Notes on the Bible:
It was an early opinion, and the opinion was probably entertained by the authors of the Septuagint translation, and by the English translators as well as by others, that the animal here referred to was the unicorn. This animal was long supposed to be a fabulous animal, and it has not been until recently that the evidences of its existence have been confirmed. These evidences are adduced by Rosenmuller, “Morgenland, ii. p. 269, following,” and by Prof. Robinson, “Calmet, pp. 908, 909.” They are, summarily, the following:
(1) Pliny mentions such an animal, and gives a description of it, though from his time for centuries it seems to have been unknown. “His. Nat. 8, 21.” His language is, Asperrimam autem feram monocerotem reliquo corpore equo similem, capite cervo, pedibus elephanti, cauda apro, mugitu gravi, uno cornu nigro media fronte cubitorum duum eminente. IIanc feram vivam negant capi. “The unicorn is an exceeding fierce animal, resembling a horse as to the rest of his body, but having the head like a stag, the feet like an elephant, and the tail like a wild boar; its roaring is loud; and it has a black horn of about two cubits projecting from the middle of the forehead.”
(2) The figure of the unicorn, in various attitudes, according to Niebuhr, is depicted on almost all the staircases in the ruins of Persepolis. “Reisebeschreib. ii. S. 127.”
(3) In 1530, Ludovice de Bartema, a Roman patrician, visited Mecca under the assumed character of a Mussulman, and among other curiosities that he mentions, he says, “On the other side of the caaba is a walled court, in which we saw two unicorns that were pointed out to us as a rarity; and they are indeed truly remarkable. The larger of the two is built like a three-year-old colt, and has a horn upon the forehead about three ells long. This animal has the color of a yellowish-brown horse, a head like a stag, a neck not very long, with a thin mane; the legs are small and slender like those of a hind or roe; the hoofs of the fore feet are divided, and resemble the hoofs of a goat. Rosenmuller. “Alte u. neue Morgenland, No. 377. Thes ii. S. 271, 272.”
(4) Don Juan Gabriel, a Portuguese colonel, who lived several years in Abyssinia, assures us that in the region of Agamos, in the Abyssinian province of Darners, he had seen an animal of the form and size of a middle-sized horse, of a dark, chestnut-brown color, and with a whitish horn about five spans long upon its forehead; the mane and tail were black, and the legs long and slender. Several other Portuguese, who were placed in confinement upon a high mountain in the district Namna, by the Abyssinian king Saghedo, related that they had seen at the mountain several unicorns feeding. These accounts are confirmed by Lobe, who lived for a long time as a missionary in Abyssinia.
(5) Dr. Sparrman the Swedish naturalist, who visited the Cape of Good Hope and the adjacent regions in 1772-1776, gives, in his Travels, the following account: Jacob Kock an observing peasant on Hippopotamus river, who had traveled over a considerable part of Southern Africa, found on the face of a perpendicular rock, a drawing made by the Hotttentots of an animal with a single horn. The Hottentots told him that the animal there represented was very like the horse on which he rode, but had a straight horn upon the forehead. They added, that these one-horned animals were rare; that they ran with great rapidity, and that they were very fierce.
(6) A similar animal is described as having been killed by a party of Hottentots in pursuit of the savage Bushmen in 1791. The animal resembled a horse, was of a light grey color, and with white stripes under the jaw. It had a single horn directly in front, as long as one’s arm, and at the base about as thick. Toward the middle the horn was somewhat flattened, but had a sharp point; it was not attached to the bone of the forehead, but was fixed only in the skin. The head was like that of the horse, and the size about the same. These authorities are collected by Rosenmuller, “Alte u. nerve Morgenland,” vol. ii. p. 269ff, ed. Leipz. 1818.
(7) To these proofs one other is added by Prof. Robinson. It is copied from the Quarterly Review for Oct. 1820 (vol. xxiv. p. 120), in a notice of Frazer’s Tour through the Himalaya mountains. The information is contained in a letter from Maj. Latter, commanding in the rajah of Sikkim’s territories, in the hilly country east of Nepaul. This letter states that the unicorn, so long considered as a fabulous animal, actually exists in the interior of Thibet, where it is well known to the inhabitants. “In a Thibetian manuscript,” says Maj. Latter, “containing the names of different animals, which I procured the other day from the hills, the unicorn is classed under the head of those whose hoofs are divided: it is called the one-horned “tso’po.” Upon inquiring what kind of an animal it was, to our astonishment, the person who brought the manuscript described exactly the unicorn of the ancients; saying that it was a native of the interior of Thibet, about the size of a tattoo (a horse from twelve to thirteen hands high,) fierce and extremely wild; seldom if ever caught alive, but frequently shot; and that the flesh was used for food. They go together in herds, like wild buffalo, and are frequently to be met with on the borders of the great desert, in that part of the country inhabited by wandering Tartars.’
(8) To these proofs I add another, taken from the Narrative of the Rev. John Campbell, who thus speaks of it, in his “Travels in South Africa,” vol. ii. p. 294. “While in the Mashow territory, the Hottentots brought in a head different from any rhinoceros that had been previously killed. The common African rhinoceros has a crooked horn resembling a cock’s spur, which rises about nine or ten inches above the nose, and inclines backward; immediately behind this is a short thick horn. But the head they brought us had a straight horn projecting three feet from the forehead, about ten inches above the tip of the nose. The projection of this great horn very much resembles that of the fanciful unicorn in the British arms. It has a small, thick, horny substance, eight inches long, immediately behind it, and which can hardly be observed on the animal at the distance of 100 yards, and seems to be designed for keeping fast that which is penetrated by the long horn; so that this species must look like the unicorn (in the sense ‘one-horned’) when running in the field. The head resembled in size a nine-gallon cask, and measured three feet from the mouth to the ear; and being much larger than that of the one with the crooked horn, and which measured eleven feet in length, the animal itself must have been still larger and more formidable. From its weight, and the position of the horn, it appears capable of overcoming any creature hitherto known.”
A fragment of the skull, with the horn, is deposited in the Museum of the London Missionary Society. These testimonies from so many witnesses from different parts of the world, who write without concert, and yet who concur so almost entirely in the account of the size and figure of the animal, leave little room to doubt its real existence. That it is not better known, and that its existence has been doubted, is not wonderful. It is to be remembered that all accounts agree in the representation that it is an animal whose residence is in deserts or mountains, and that large parts of Africa and Asia are still unexplored. We are to remember, also, that the giraffe has been discovered only within a few years, and that the same is true of the gnu, which until recently was held to be a fable of the ancients.