NATURAL HISTORY SOCIETY OF GLASGOW. 133 



informs me that the females, of which there were four, are all 

 alike in plumage, being brown on the breast, while the upper 

 parts are beautifully marked with transverse bars of light brown 

 over a ground colour of drab, the brown being of greater density 

 in some individuals than in others. The males differ markedly 

 from the females, having a preponderance of the rich grouse-like 

 chestnut-brown on the back as well as on the breast. Mr Sim 

 had previously compared these birds with Sir William Jardine's 

 description and plate of his Perdix cinerea, var. montana (Nat. Lib., 

 Ornith., vol. iv., plate 2), and found them to agree with that 

 variety.^ Mr Robert Gray mentions ('Birds of the West of 

 Scotland,' p. 242), a pair of birds which he tells us "agreed 

 precisely " with Sir William Jardine's bird, and which he saw in 

 Dundee. These had been killed on the higher grounds of Forfar- 

 shire, and the keeper distinguished them by name as hill par- 

 tridges. As I have heard the term applied in various districts, hill 

 partridges are simply smaller and darker birds, living generally on 

 the higher ground bordering the moors, and often found amongst 

 the heather itself. Still, in the present instance, it would almost 

 appear as if this variety had been induced b}^ food and locality, if 

 we look at the almost perfect grouse-colour, especially of the male. 

 Actual melanism is, as we know, caused in some species in 

 confinement by an over-diet — or an exclusive diet — of oily hemp- 

 seed, and I believe this will also be found to cause melanism in 

 wild species, as for instance in this Yellow-hammer; or, as I am 

 inclined to imagine, may be the cause in this North Russian Sand 

 Martin. Is it not possible also that some peculiar food may have 

 in like manner affected these and other partridges, (obtained, be 

 it remarked, in the same locality) '? Might not a continuous diet 

 of this food, whatever it may have been, influence the colour, 

 reaching through the pores of the skin, extending down the 

 feathers, or affecting the growth and colour of the new feathers 

 during the moulting season? Or again, if in course of time the 

 blood became impregnated by some subtle poison or property of 

 the food, might not these birds in breeding perpetuate the new 

 stock? I believe the causes of variation in wild species are not 

 fully worked out, and that there is room for inquiry and careful 



* The Editorial criticism in this connection (Zool. 1877, p. 229), applies to 

 the incomplete newspaper report of this paper. I have explained the inaccu- 

 racy in a note to the June No. of the Zoologist. — J. A. H. B., May 19th, 1877. 



