A peculiar thing about gemsbuck is that females are virtually indistinguishable from males (unless you look carefully at the right places), being of the same size and having the same markings and horn configuration. The horns of male gemsbuck tend to be thicker at the base than those of females and somewhat shorter. Longtime observers of gemsbuck, like one of our guides, Hannes Steyn, say that the males wear down their horns by rubbing and polishing them in the sand. True or not, the record books list many females. In trophy-book terms, horn length over 35 inches is pretty good and anything over 42 inches is spectacular. Most of the gemsbuck listed in the record books were taken in the general area where we were hunting, and Dirk, my guide and expert judge of trophies, was confident the animal we were watching would easily top 40 inches, perhaps by several inches. But it was possible that the almost perfectly matched horns gave an illusion of extra length because the animal was lying down. We'd have to make a final judgment when the animal stood up. As the minutes ticked into mid-morning the warmed Kalahari atmosphere began to boil with mirage, making the horns of my gemsbuck seem to wriggle like snakes dancing on their tails.