[Theiris] is characterized by prominent, pale, radiating stripes, the ciliary processes. These, from 70 to 80 in number, are meridionally disposed ridges which end anteriorly in blunt club-shaped extremities. They are about 2 mm. long, 0-5 mm. wide, and rise 0-8 or 1 mm. from the surface, but there are large individual variations. In structure these processes are almost entirely vascular, for the choroid losses its chorio-capillaris in this region, and the vessels now form one layer running antero-posteriorly in parallel bundles. The anterior surface of the ciliary body (the base of the triangle) is practically entirely obscure. Internally it is continous with the root of the iris, and round the periphery the trabeculae of the angle of the anterior chamber find partial attachment to it ; a narrow strip is left between these two regions which take part in the formation of the posterior wall of the anterior chamber, but frequently this intermediate region is encroached upon by the innermost lamellae of the trabeculae or by an extension downwards of the structure of the iris.