1895. SEXUAL SELECTION. 401 



Thus one species of " higher animal," at all events, must content 

 itself with any physiological makeshift it can find to explain the 

 production of its ornamental colours. Perhaps others of its order fare 

 no better. And whoever is inclined to generalise from this conclusion 

 will feel how difficult it is to assume, on the Darwinian hypothesis of 

 preferential mating, that the aesthetic faculties attributed to female 

 birds, and employed by them in the improvement of male fashions, 

 should lie dormant throughout the next Order, Reptilia, and after- 

 wards suddenly reappear, in their full complexity, among the 

 Lepidoptera and Arachnida. Such an assumption must, indeed, be 

 rejected, if only on the ground of the close analogy between the 

 secondary sexual characters of birds and those of reptiles. 



I should like to append one or two remarks on the melanic 

 insular races of L. vmvalis, whose genetic development has some 

 bearing on the question of sexual selection. In speculating on the 

 origin of their strange coloration, it would be satisfactory if we could 

 dispense with the all-explaining " external influences " ; for their — 

 biologically — isolated position becomes more apparent if neither 

 physical nor economic conditions have contributed to this result. 



Now, as to the first of these, although dark coloration in this class 

 of animals has been ascribed in some instances to moist surroundings, 

 in others to the action of light-rays (whose irritating influence on the 

 smaller vessels may induce a deposit of pigment under the epithelial 

 layers), yet, in the case of island varieties, exterior agents such as 

 these must affect either all of them or none. Nor have economic or 

 social causes, arising out of the relation of these races to other 

 organisms, played a part ; the " protective coloration " hypothesis 

 which has been advanced does not seem tenable, for the following 

 reasons: — (i) If the dark upper surfaces of the Faraglione-lizard are 

 adaptively-imitative of the fissures, etc., in the rock,^ it is surprising 

 that the lizards oa the neighbouring and similarly coloured islet 

 should be, not black, but sky-blue- on that portion of the body. (2) 

 The summit of the outer rock is covered with vegetation, and has a 

 certain depth of soil (the elder Spadaro, who used to ascend it, 

 planted a crop of potatoes there). Thus the adaptation could refer 

 only to the sides. (3) On other Mediterranean islets of the same 

 colour and geological structure as the Faraglione the lizards are 

 differently coloured. (4) The fact that the Faraglione race is excep- 

 tionally tame (more so than any other insular or continental race with 

 which I am acquainted), and that (5) the females are almost as 

 brightly tinted as the males, indicate they have few, or no, enemies, 

 and therefore stand in no need of protective coloration. 



I must apologise for this digression. It would be interesting if 

 races like L. lilfordi, L. ccerulea, etc., could be shown to have been 



1 Eimer, " Studien auf Capri," ii., pp. 36 el sqq. 



- Eimer, " Variiren, etc.," p. 154. 



2 F 



