J. K. DrKUDKN 1«1 



As iiutinl I'lirlirr. tanning pracliri' him rMtnhli.shcd ns clciirly as cmld 

 he fxpt'cUni that thr diffrrt'iit '* |H»ints " of tin* plumes an* factorial in 

 their U^haviour. and an they vary in thr varioiin Htniins a wparaU* 

 >(i*nninal n'pn^srntation for vach may hv juHsumrd. Kven Mtich a simpl*- 

 structuml part ax the central shaft, of the feather shows many ditVerent, 

 typos which ap|H»ar either distinct or as inU-rmediates in crosses. The 

 length of the Imrhules an<l tht'ir closeness on the harhs are also inatt<M-s 

 i>f much economic im|>ortanc<' in determining the "density" of tin- j)lunies. 

 and the tarmer never «|uestions their distinctness in breeding. At the 

 present stage of the ostrich industry, where crossing is pnvctised t<» such 

 a high degri'e. the factorial analysis (jf the individual j)hnue would he 

 a prolongiMi undertaking, hut will become feasible as the farmer finds 

 himself in a j)osition to build up pure strains. 



SCUTELLATION oF MiDDLK ToK. 



Along the tVont of the tiirsus extends a series of large, nearly rect- 

 angular sciiles, which in most c.ises continues uninterruptedly to the end 

 of the big middle toe. Over the leg the contiguous edges of th<* scales 

 simply meet, but they are imbricated where the tarsus joins the toe and 

 also over the latter, thus allowing for the bending movements of the 

 toe during walking and running. Along the tarsus the scales retain 

 approximately the same size, but at the junction with the toe they 

 usually become somewhat smaller, enlarging again distally. Occasionally 

 a distinct break in the continuity (jccurs at the joint, several of the large 

 scales disappearing and being replaced by insignificant ones like those 

 which cover the surface of the limb generally ; and in rare cases a second 

 break in the continuity takes place over the joint about the middle of 

 the toe, thus giving a proximal and distal series of digital scales (Text- 

 fig. 2, p. 182). 



The number of scales fluctuates in different individuals, and also on 

 one limb as compired with the other; and occasionally irregularities are 

 introduced owing to single scales being partly subdivided. At the 

 breaks the large scales tend to pass insensibly into the small scales of 

 the limb, hence any enumeration is only approximate. A few countings 

 are given in Table VIII, p. 188. 



The break in the continuity occui*s rather rarely, especially in 

 southern ostriches. Out of 20 Cape birds of mixed breeding only one 

 showed an interruption, while in 20 mixed Nigerian birds a single break 

 occurred in three c;ises and a double break in two. As the figures in 



