F/A-18 Hornet. The Models "A" through "D" had the semi circular inlets as seen here. Pay attention to how the fuselage forms into a "humpback" just behind the cockpit. At first look the "LEX" seems just Anhedral but the more you look it seems to be of a complex polyhedral design. Probably due to the width of the LEX. "L.E.X. = Leading Edge eXtension"