1. County of Los Angeles, Comparative Medicine and Veterinary Services, 12824 Erickson Avenue, Downey, Californa 90242, USA
2. Present address and address for reprints: California Veterinary Diagnostic Laboratory, 2789 South Orange Avenue, Fresno, California 93725, USA
3. Los Angeles Zoo, 5333 Zoo Drive, Los Angeles, California 90027, USA
4. Center for Reproduction of Endangered Species, Zoological Society of San Diego, San Diego, California 92112, USA
5. Dr. Edwin B. Howard died 9 July 1987