142 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



nearly all the numerous species of snakes, he should have added a tiny 

 rudiment in the case of the Python and even in that case should 

 have maintained his ideal very inefficiently, inasmuch as only two 

 limbs, instead of four, are represented ? How much more reasonable 

 is the naturalistic interpretation; for here the very irregularity of 

 their appearance in different species, which constitutes rudimentary 

 structures one of the crowning difficulties to the theory of special 

 design, furnishes the best possible evidence in favour of hereditary 



FIG. 18. Aptcryx anstralis. Drawn from life in the Zoological Gardens, 

 | nat. size. The external wing is drawn to a scale in the upper part of the cut. 

 The surroundings are supplied from the most recent descriptions. (From 

 Romanes.) 



descent; seeing that this irregularity then becomes what may be 

 termed the anticipated expression of progressive dwindling due to 

 inutility. Thus, for example, to return to the case of wings, we have 

 already seen that in an extinct genus of bird, Dinornis, these organs 

 were reduced to such an extent as to leave it still doubtful whether so 

 much as the tiny rudiment hypothetically supplied to Figure 15 was 

 present in all the species. And here is another well-known case of 

 another genus of still existing bird, which, as was the case with 

 Dinornis, occurs only in New Zealand (Fig. 18). Upon this island 

 there are no four-footed enemies either existing or extinct to escape 

 from which the wings of birds would be of any service. Conse- 



