This is a question about the squirrel monkeys at London Zoo. Up until 1990, the inventory listed the zoo as holding common squirrel monkeys (Saimiri sciureus); these departed in that year. Squirrel monkeys returned in 2005 (I think this was when "Meet The Monkeys" was opened), and that year's inventory lists Saimiri sciureus as being in the collection. The following year they - apparently - departed, and in came Bolivian squirrel monkeys (Saimiri boliviensis boliviensis). S sciureus were listed again the following year, and until 2010. S bolivinsis have been listed ever since (except for 2009, when they weren't). Is the collection of squirrel monkeys shifting in this manner? Or is the taxonomy of these animals open to debate? Or are ZSL making errors? Does anybody have light to shine on this one?