Bat Penis Bones (IMAGE) Field Museum Caption The bacula, or penis bones, of the bats described in this paper. The tiny bones have been dyed red so that they're easier to isolate. Credit (c) Ara Monadjem Usage Restrictions Please include credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.