J. K. DrKunKX 



17:> 



first n»w ol* pluiiies, llu' win^ t|uillN nr rrmi^tM, iialmlrM the iainiliiir 

 whiu? plmiici* of the ostrich which arc by far l\\v most vahuihli* ns coin- 

 pnrLMJ with the first iiml «ccon<l rows of upjMT-cnvcrts which an* also 

 clipptHl, and an* hhick in thr cock and ^rcv in thr hen. Ah the coverts 

 altiTnati' with the wing <|uills the innnbrrs in all the rows an* definit<'ly 

 c*>rrelate<l, .h«» that for pur|)oses of coniparisnn aiunn^^ ditV^nnt birds 

 attention can be confined to the first n»w. thr nini^^'s (PI. VII, fi^^s. I 

 and 2) 



North African Ostriches. The first-row fcathei-s on each win^^ havr 

 been connted on 25 of the original imported North African birds and 

 the n^sults are given below. It will be noted that a ditterence of one or 

 two phinies is often found between one wing anri the other, })ut the 

 cocks and hens show fto distinction. The number on the wing varies 

 from 38 to 39, the arithmetical mean of the series bi'ing 3()-54 ; repre- 

 sentinl gniphically they approximate to a normal fre(juency curve with 

 the mode at 3(). Manifestly the birds represent a mixed i>opulation, a 

 result of indiscriminate breeding in a race in which the numbers difier 

 by small amounts; but indications are not wanting that a pure line win 

 be built up of each number. We may regard each bird as heterozygous 

 with regjird to number of plumes, and a mixture of the kind given below 

 is what would be expected seeing that the birds come from a single area 

 in North Africa where no farming selection is practised. 



TABLE IV. 

 First-rou^ Plumes on Wings of Imported North African OstricJies. 



The number of plumes on the wings of 15 pure North African chicks 

 reared at Grootfontein from the importation, are also represented and 

 give approximately the same arithmetical mean as the above, namely 

 36*7, though without the low numbers 38 and 34. The chicks are from 



