In yesterday's post I mentioned the cockatrice. I made reference that it was only found in the King James Version and left it at that. The Cockatrice is a mythological creature with the body of a rooster, and the tail of a serpent. The cockatrice was first described late in the twelfth century, based on an entry in Pliny's natural history. It was a duplicate of the basilisk, but with wings, and a bit reversed in the process of how it was formed.
The question is if the cockatrice wasn't imagined until the 12 century AD, how did it find itself in the stories of Isaiah and Jeremiah written thousands of years before. It is most likely that the writers of the King James Bible got the idea from the LXX, which translates the Hebrew word צפﬠוני as basiliskos. The Hebrew word צפﬠוני, according to Holladay's Hebrew and Aramaic Lexicon refers to a poisonous snake or an Aegean viper. The Greek word basiliskos likely also refers to a poisonous snake rather than the basilisk of the middle ages. This is where it is easy to see how the writes of the King James Bible made their mistake in the 17th century. They followed the trend set by John Wyclif, who had translated from the LXX and called the created a basilisk.
It is interesting to note the word צפﬠ, most commonly used in its form צפﬠוני, is used five times in the Hebrew text Isaiah 14:29, 11:8, 59:5, Jeremiah 8:17, and Psalm 23:32. The word is translated "cockatrice" 4 times in the KJV, but in Psalm 23:32 it is translated as "adder." So even the KJV translators were not consistent in their translation of the term.
The ESV translates the term as adder in all cases, and the NIV translates it as viper. The original term therefor meant a poisonous snake, the KJV writers were confused by a similar term in their day which referred to a mythological creature, and newer translations such as the ESV and NASB have corrected such error.