The corneal lens of the tiger beetle larva was treated as a thick biconvex lens, which was defined by following morphological parameters: diameter (D), thickness (t), and the radii of external and internal curvatures (re and ri). These values were obtained for the posterior eye by observation of semi-thin plastic sections (Table 1). Although re
and ri are expressed as vectorial values as well as focallengths (f and f0) in Eqs. (1)–(5), their absolute values are given in the tables and the following description. The distance from the posterior margin of the corneal lens to the retina (the lens–retina distance) measured in each section for the central region and peripheral (anterior and posterior) regions of the eye are also given in Table 1. The size of aperture (A) that is formed by a circular pigmented envelope around the lower part of the corneal lens is also given in Table 1. The size of the lens varied from 430 lm
to 525 lm, and other parameters also varied. These variations might partly result from inter-individual variation in the size of eyes, because other morphological parameters
were positively correlated with the diameter of the lens (Fig. 9A).