402 



NATURAL SCIENCE. Dec. 



formed, so to speak, of their own sweet will, and free from the 

 restraint of Natural Selection. This seems to allow wider scope to 

 sexual preferences. But I can find no particle of evidence that the 

 curious tints of these varieties or certain structural peculiarities have 

 been thus acquired. The males are exceptionally pugnacious,^ of 

 large size (due to a succession of combative ancestors), and in 

 unusual preponderance over the females- ; but this is negative evidence. 



To obtain some idea how these insular races have gradually 

 deviated from the parent stock, one may compare the lizards on the 

 town-walls of ancient Paestum, a comparatively isolated area, with 

 the common Neapolitan form. Both the var. maculata and elegans are 

 here represented, but they are larger in size, and the throat and lower 

 surfaces are suffused in early spring with a decided blue tinge. 

 Perhaps they would become a biological species analogous to the 

 Faraglione race, if the innate tendency to increase the supply of 

 normal pigmentation were uncontrolled ; as it would be, if greater 

 isolation destroyed the equilibrium between competing species and 

 rendered superfluous all protective coloration. This, I think, is 

 what has taken place with the Faraglione lizard and others ; but such 

 changes are not efTected even on small islands of the size of Capri or 

 Malta, for here the struggle for existence, so far as L. mnyalis is con- 

 cerned, is as severe as on the mainland. 



Whoever turns to these melanic races to elucidate the problem of 

 sexual selection will find them instructive from at least two points of 

 view. They illustrate, in the first place, a change in the direction of 

 variation. I do not propose to criticise Professor Eimer's suggestive 

 " Law of Undulation," beyond saying that even if the archetype of 

 this species was longitudinally barred, and if these bars show a 

 tendency to break up into vertical markings, it does not necessarily 

 follow that all other forms are intermediate in the sense of " less 

 advanced," and represent so many stages of standing still {Gcncpistasis) 

 in the course of phyletic development. The principle of evolution 

 seems to be broader. The var. elegans, for instance, or the Faraglione 

 iizard, whose primordial [?] stripes can be plainly detected on speci- 



1 Five out of ten males from the ¥\\^a. rock had their tails broken off short, 

 presumably during occasional encounters. This is far above the average of such 

 mutilations. Bedriaga and Eimer testify to the combativeness of the Faraglione 

 lizard. The females are said to be almost as bellicose as the males. 



'■^ This is as yet only a supposition, and remains for future observers to de- 

 termine. The numerical proportion of the sexes in many animals depends, to some 

 extent, on climate, nutrition, etc. On the Filtla reck the proportion obtained was 

 ten males to four females, and from the Faraglione four males to two females, 

 although the females are everywhere more easily caught. This disproportion is not 

 borne out by the small material in the British Museum, but Professor Eimer notes 

 that " much fewer " female Faraglione lizards came into his hands than males, a 

 fact which he attributes to their greater shyness. I have found, on the contrary, 

 that the male wall-lizards are always more shy and active than the other sex, and 

 this accords with the experience of Professor Leydig (" Die in Deutschland lebenden 

 Arten der Saurier," p. 157). 



