(also known as Niels Steensen, and the Father of Geology) Anatomist and priest, born Copenhagen, Denmark on 10 January 1638; died at Schwerin, Germany on 26 November 1686. Among his anatomical achievements was the discovery of the excretory duct of the parotid glands and the circulation of the blood in the body. When the unappreciative Danes finally called for him he had become a Catholic in Florence and as such could not return. In Italy he made many geological discoveries and was the first to explain petrifactions in the earth. Ordained in 1675, he was made vicar Apostolic for the northern missions.