USE AND DISUSE OF ORGANS. 1S5 



of the organs of flight. With this was combined, as 

 these beetles show, no degradation of organization, but, 

 on the contrary, a higher and extremely advantageous 

 development of other organs, the manducatory and 

 locomotive apparatus. A general reduction of the 

 power of flight has been shown in the beetle fauna of 

 many islands. Thus in Madeira, of 550 species, over 

 200 fly imperfectly or not at all, and for this there is 

 no explanation but natural selection. Here the less 

 good and enterprising flyers had the advantage, while 

 the others were blown into the sea and eliminated. 

 The non-application of a previously attained special 

 perfection is advantageous in the " struggle for 

 existence." 



In several families of lizards, some genera are ser- 

 pentine, as they are termed, which, with elongated 

 bodies, possess either fore-legs only (Chirotes), or 

 merely rudimentary hind-legs (Pseudopus), or no ves- 

 tiges of legs (Anguis). They bear the same relation 

 to the great class of normally four-legged lizards as 

 the non-flying insects to their own class. They have 

 not been arrested in their development, nor are they 

 animals in process of evolving four legs ; but, as 

 Fiirbrlnger has demonstrated from the history of 

 development and comparative anatomy, their limbs, 

 and — if these arc entirely absent — the remains of the 

 pectoral and pelvic arches and the sternum bear 

 indubitable marks of the abortion of a once com- 

 plete apparatus. Further comparison shows that this 

 atrophy reaches its climax in the snakes, but that it 

 is compensated for by the ribs and intercostal muscles 

 havincr undertaken the work of the limbs. Here, 



