I Quagga 



249 



in Giraffes as we proceed from South to North- 

 east Africa, is that it is precisely the reverse of 

 that among the Quaggas and Bonte-quaggas. . . , 

 In the case of the Quagga group, a satisfactory 

 and sufficient explanation of the reason for the 

 colour-change has, I think, been given by Mr. 

 Pocock. As regards the cause of the chango in 

 the reverse direction presented by the Giraffes, 

 I have not hitherto been able to obtain any clue ». 



La spiegazione data dal Pocock pel caso dei 

 Bonte-quagga e dei Quagga si fonda su conside- 

 razioni intorno all' adattamento e, mi pare, alla 

 scelta naturale, poiché certo quella variazione 

 deve essere stata portata da un adattamento a 

 condizioni nelle quali meno sarebbe stata protet- 

 tiva ed utile la primitiva veste riccamente adorna 

 di contrasti, e meglio doveva servire la nuova 

 veste più dimessa: 



Ecco le parole del Pocock : u In correlation 

 with the adoption of a life in the open, a new 

 method of concealment by means of shadow coun- 

 teraction was required, and was gradually per- 

 fected by the toning down of the stripes on fche 

 upper side and the suppression of those on the 

 hind-quarters, belly and legs. The same alignment 

 of the white on the rump and belly may be seen 

 in many Antelopes ». 



Sarebbe dunque stato il passaggio, realmente 



