From the alcoholic extract of the seeds of Casimiroa edulis, La Llave (Rutaceae) F. B. Power and T. Callan1) obtained 0,021 p.c. (computed with reference to the dry seeds) of a volatile oil with the following properties: d20o 0,9574; optical rotation in a 25 mm. tube - 2°25'; boiling temperature mostly below 130° (25 mm.).