326 LAWS OF VARIATION. Chap. XXV. 



furnished with a vascular rim in correlation with intra- 

 puimonaiy deposition of tubercles. In other cases of phthisis 

 and of cyanosis the nails and finger-ends become clubbed like 

 acorns. I believe that no explanation has been offered of 

 these and of many other cases of correlated disease. 



What can be more curious and less intelligible than the 

 fact previously given, on the authority of Mr. Tegetmeier, 

 that young pigeons of all breeds, which when mature have 

 white, yellow, silver-blue, or dun-coloured plumage, come out 

 of the egg almost naked ; whereas pigeons of other colours 

 when first bom are clothed with plenty of down ? White 

 Pea-fowls, as has been observed both in England and France, 34 

 and as I have nyself seen, are inferior in size to the common 

 coloured kind ; and this cannot be accounted for by the 

 belief that albinism is always accompanied by constitutional 

 weakness ; for white or albino moles are generally larger 

 than the common kind. 



To turn to more important characters : the niata cattle of 

 the Pampas are remarkable from their short foreheads, 

 upturned muzzles, and curved lower jaws. In the skull the 

 nasal and premaxillary bones are much shortened, the 

 maxillaries are excluded from any junction with the nasals, 

 and all the bones are slightly modified, even to the plane of 

 the occiput. From the analogous case of the dog, hereafter 

 to be given, it- is probable that the shortening of the nasal 

 and adjoining bones is the proximate cause of the other 

 modifications in the skull, including the upward curvature 

 of the lower jaw, though we cannot follow out the steps by 

 which these changes have been effected. 



Polish fowls have a large tuft of feathers on their heads ; 

 and their skulls are perforated by numerous holes, so that a 

 pin can be driven into the brain without touching any bone. 

 That this deficiency of bone is in some way connected with 

 the tuft of feathers is clear from tufted ducks and geese 

 likewise having perforated skulls. The case would probably 

 be considered by some authors as one of balancement or 

 compensation. In the chapter on Fowls, I have shown that 



34 Rev. E. S. Dixon. ' Ornamental Geoffroy, ' Hist. Anomalies,' torn. i. 

 Poultry,' 1848, p. Ill; Isidore p. 211." 



