OSAC discourages the retention of any of its specimens.   In some cases, retentions may be permitted if researchers are identifying unidentified material that includes series of duplicate specimens.  

Specimens that represent: (1) type material, (2) morphologically and geographically unique specimens, (3) scientific voucher specimens, and (4) previously determined material (even if is deemed to be mis-identified) are generally not available for retention.  

Exceptions to the above rules may be made, especially in the context of exchanges that will expand our holdings taxonomically or geographically or that includes type material.  However, any exceptions must be agreed on in writing prior to the return of the loan.