An account is given of a generally unrecognized fascial ligament (lig. temporo-pterygoideum) found to occur in eutherian mammals. This structure is a functional specialization of the salpingo-palatal fascia, developed in response to the activity of the palatal tensor and levator musculature. The ligament is attached superiorly to the Eustachian process of the temporal bone and inferiorly to the hamular process of the medial pterygoid lamina. It is responsible for the development of both these processes, which, in the macerated cranium, testify to the original presence of this ligament.