218 Letters, Extracts, and Notes. [Ibis, 



111 the adult montana Partridge the two prevailing colours 

 have, so to speak, run. The bufF-colour has spread over the 

 whole head and neck, the chestnut has spread over the body 

 and wings, and the result is a bird singularly unlike the 

 normal Partridge. This strange variation was first described 

 (as a distinct species) from Lorraine, where it seems to have 

 occurred frequently. But it has occurred also in Spain, 

 in Rumania, in Norfolk, in Northumberland, in the 

 Lowlands of Scotland ; probably in many other districts 

 too. In any case it seems plain that it is not a localized, 

 freak, but a variation which is liable to crop out in the 

 partridge stock wherever the species is found. That alone 

 would be enough to snggest tiiat the montana form, with 

 its remarkable constancy over a wide geographical range, 

 is due to some such definite factor in inheritance as is dealt 

 in by the Mendeliaus — perhaps to the loss of one of the 

 germinal factors regulating the development of the colour- 

 pattern in the normal bird. But there is also evidence of 

 another kind pointing in the same direction. If, as I am in- 

 clined, to suggest, the montana colour-pattern is "recessive'' 

 (in the Mendelian sense) to the normal colour-pattern, we 

 should expect (I) that when it does appear it would only 

 be in, roughly, a quarter of the brood, except (2) when 

 both parents are of the montana form, and then the whole 

 brood should be montana birds. This expectation does, 

 in fact, seem to be realized as far as the evidence goes. 

 In mici-Northumberland, where montana Partridges are of 

 comparatively frequent occurrence, there are usually only 

 about two birds of that form in a covey. Being very con- 

 spicuous they are nearly always shot, and with equal 

 regularity regarded as hybrids with the Red Grouse. There 

 is little chance in nature of two adult montana birds sur- 

 viving, pairing, and rearing a brood. Nevertheless this 

 seems to iiave happened at least twice in Northumberland, 

 for Mr. George Bolam, in his ' Birds of Northumberland 

 and the Eastern Borders,' pp. 473-7, records two cases 

 in which whole coveys were of the montana form, and in 



