Letters, Extracts, Notices, i^c. 569 



the argument from analogy — that the form of the haemo- 

 globin crj'stals in mammals differs considerably. Dr. Wick- 

 mann also asserts that there are no eggs free from pigment. 

 White eggs contain a white pigment. This fact is of great 

 interest, as white pigment is exceedingly rare in the animal 

 kingdom, a white colour being nearly always due to optical 

 causes. 



LIV. — Letters, Extracts, Notices, ^c. 



We have received the following letters, addressed to the 

 Editor, since our last issue : — 



Sir, — In Sharpe's edition of Layard^s ' Birds of South 

 Africa' (p. 581), the question is raised as to whether wild 

 specimens of Nurnida coronata are found with wliite quill- 

 feathers; and Mrs. Barber, whose knowledge of the species 

 is very considerable, is reported to have replied in the 

 negative, so far as her experience was concerned. 



At this season of the year (winter), in Pretoria, quantities 

 of wild Guinea-fowls are shot in the country districts and 

 forwarded to Johannesburg and Pretoria for sale. I have 

 thus procured examples of several good species; and among 

 a number of Knorhaan, Teal, and Guinea-fowl shot in 

 the Orange Free State and consigned to a poulterer here, I 

 secured a fine specimen of this variety, proving incontestably 

 that it does occur in a wild condition. 



In this specimen all the quill-feathers are white; it also 

 differs from the ordinary bird in its paler ground-colour 

 — pale, not dark grey — but has no trace of the white breast, 

 which the tame breed possesses. I could not determine the 

 sex, as it is necessary to forward these birds in an eviscerated 

 condition. I am, Sir, 



Yours &c., 



Pretoria, Transvaal, W. L. Distant. 



.Tune 1894. 



Sir, — In Dr. Sharpe's remarks in your last number (above, 

 p. 422) on the generic names Microjms and Microtarsus, 1 



