The main veins of the Nile turtle Trionyx triunguis exhibit certain features in common with thorn of diving mammals. The jugular system is greatly reduced and the head is drained lwgely by an intravertebral vein. A peculiar snastomosing of the venous system in several parts ensures venous circulation under all conditions. The absence of valves from certain veins, the presence of venous plexuses and retia mirabila and othermo difications of the veins to suit the diving habit, are described.