This specimen was labelled as Saguinus fuscicollis. Unfortunately ZTL now lists at least four forms (subspecies) which were held at Jersey in the '70s and thereafter. After looking at the paper 'Taxonomic review of the New World tamarins' by Rylands et al, I think it may be Saguinus illigeri (Saguinus fuscicollis illigeri). I would welcome second and indeed third opinions.
