Cases of variation similar to those now adduced among butterflies might be increased indefinitely, but it is as well to note that such important characters as the neuration of the wings, on which generic and family distinctions are often established, are also subject to variation. The Rev. R.P. Murray, in 1872, laid before the Entomological Society examples of such variation in six species of butterflies, and other cases have been since described. The larvae of butterflies and moths are also very variable, and one observer recorded in the _Proceedings of the Entomological Society for_ 1870 no less than sixteen varieties of the caterpillar of the bedstraw hawk-moth (Deilephela galii). _Variation among Lizards_. Passing on from the lower animals to the vertebrata, we find more abundant and more definite evidence as to the extent and amount of individual variation. I will first give a case among the Reptilia from some of Mr. Darwin's unpublished MSS., which have been kindly lent me by Mr. Francis Darwin. "M. Milne Edwards (_Annales des Sci. Nat._, I ser., tom. xvi. p. 50) has given a curious table of measurements of fourteen specimens of Lacerta muralis; and, taking the length of the head as a standard, he finds the neck, trunk, tail, front and hind legs, colour, and femoral pores, all varying wonderfully; and so it is more or less with other species. So apparently trifling a character as the scales on the head affording almost the only constant characters." [Illustration: FIG. 1.--Variations of Lacerta muralis.] [Illustration: FIG. 2.--Variation of Lizards.]