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 Darwin's unpublished MSS., which have been kindly lent me by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.]
As the table of measurements above referred to would give no clear
conception of the nature and amount of the variation without a laborious
study and comparison of the figures, I have endeavoured to find a method
of presenting the facts to the eye, so that they may be easily grasped
and appreciated. In the diagram opposite, the comparative variations of
the different organs of this species are given by means of variously
bent lines.
Pages:
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111