170 LETTERS TO THE EDITOR. 



figure in the Ibis, and two of these — a Kutch and a Sirsa 

 bird — shot in just the same Tamarisk jungle in which Mr. 

 Tristram procured his specimens. I may add, that between 

 these specimens and the somewhat darker examples a perfect 

 gradation of tint is exhibited. I am afraid we must say of 

 C. tamaricis, " Delenda est." 



At rAGE 487 of Vol. V, I described a supposed new Arachno- 

 thera under the name of A. simillima. Since then Captain 

 Shelley, to whom I sent the type, has expressed the opinion that 

 the bird was abnormal, and he thought it probable that a second 

 like it would never be obtained. I had almost become a convert 

 in this view, when lo and behold our people sent us up from 

 near Malacca three more specimens precisely similar to the type, 

 two of which appear to be not only quite adults, but rather 

 old birds. 



Having now four specimens of this form, all of them of 

 precisely the same type, I hardly see how we can avoid the con- 

 clusion that they represent a distinct species. 



This, however, I must leave to my friend Captain Shelley, who 

 has, I believe^ figured the type. 



fitters k ilje €Mior. 



Sir, 



In the gardens of the Zoological Society of London there 

 have been living since July 1875 two specimens of Oiogyps 

 calvus from India v/hich appear to be fully adult, and of which 

 one has the irides of a pale straw color, whilst in the other they 

 are of so dark a brown as to be undistinguishable from the 

 pupil by a spectator standing outside the bird's cage. 



Mr. Bartlett, to whom I am indebted for calling my atten- 

 tion to this circumstance, informs me that the color of the 

 irides in each bird was the same as it is now, when they 

 arrived in the gardens in 1875. 



Is this difference in the color of the irides sexual ? I am 

 disposed to think that it may be so, from the fact that in the 

 adult male of the South American Condor, the irides are of a 

 pale straw color, whilst in the adult female they are a very 

 deep carbuncle red. 



I am, &c., 



J. H, Gurney. 



mh November 1877. 



