biconvex

The atlas (fig. 71) is remarkable, consisting of four pieces, and the first caudal is biconvex.

The first caudal vertebra of modern Crocodilia is biconvex, and in the Chelonia all types of vertebral centra are found.

The coloured corpuscles of amphibia as well as of nearly all vertebrates below mammals are biconvex and elliptical.

The lens is biconvex in diurnal mammals, but in nocturnal and aquatic it is spherical.

The holochroal eyes are of two kinds, one with plano-convex and one with biconvex lenses.