Direct measurements on the orientation of the reflecting surfaces in the tapetum of Squalus acanthias, and some observations on the tapetum of Acipenser sturio

Direct observations on the reflecting layers in the tapetum of the spur dog Squalus acanthias confirm the orientations of the tapetal reflecting cells which were previously found histologically (Denton & Nicol, 1964). Surface views of the tapetum show the outlines of the exposed surface of the tapetal plates as ‘polygons’. The long axes of these polygons are parallel with the plane of the tissue on which they lie and the polygons are only inclined to this plane across their short axes. The angle to which they are inclined increases as we move towards the periphery of the eye.