Much of our knowledge about the nineteenth-century natural history boom resides with the collectors themselves and their collections. We know much less about the conduct of the global trade that made collecting possible. That such a trade occurred in the face of significant obstacles of distance, variable prices, inadequate information, and diverse agents makes our knowledge deficit the more significant. William John Macleay, based in Sydney, built his significant natural history collection by trading locally as well as across the globe. (...) Our study of Macleay measures his complete set of trading transactions at a time of rapid expansion of his collection. It analyses how he chose between different forms of exchange and agreed fair value in order to complete long-distance specimen trading. (shrink)