28
The Wagtails of India.
The well-marked black monstacliial line which has been
considered the distinguishing' character of Hodgsoui is clearly
merely a stage of plumage. Exactly the same chai-acteristic line
is met with in Persouata, about March^ when the black of the
breast begins to ei-eep up the upper part of the throat to the
chin; and this moiistachial stripe shews itself again in September^ when the chin has l^ecome white and the throat has begun
to exhibit snowy speckles ; in fact both in Luzoniensis, Scop.,
(which isj I suppose^ the name that must stand founded on pla'"je
29 of Sonnerat's Voyage a la Nouvelle Guinee) and Pei'sonata,
in both of which I have shewn that the chin and throat become
ultimately quite blacky it is the feathers along this so-called
moustachial line which first, (as compared with those of the
immediately contiguous parts) assume, and latest divest themselves of, the black tint.
In the breeding plumage the female oi I/uzoniensis differs only in its smaller size, and the somewhat browner black of the buck, somewhat as may be observed in the breeding plumage of the two sexes of Madrasjoatana.
Of the cold weather plumage of this species, I cannot speak with any great certainty, and on this point further careful observations are I think necessary. I have as yet obtained but few specimens showing the transition from the grey of the winter to the black of the summer plumage and vice versa ; but at the same time there is no doubt of the fact, and it would be very interesting to trace the changes in plumage from October to March, as I have endeavoiired to trace those from April to September. It may be that Liigtthns, as supposed by Schlegel, is a cold weather form of Luzoniensis, but the distribution of the black and white in the former species hardly looks to me compatible with this supposition.
Of the grey -backed species I may premise that I myself have never been satisfied that Dulchmensis really deserves specific separation from Alba, any more than I am satisfied that Pratincola Indica and Pratincola Uuhicola i-eqitire distinct specific appellations. The two forms so closely resemble each other, that all that I shall have to say about the one will, I believe, be equally applicable to the other. Certainly there is no constant difference in size in the two species. I have five male Alha before me from different places on the Continent, the wings of which vary from 3'4 to 3'6 inches ; and I have forty specimens of Bukhunensis about half of which are male, and in this latter sex the wings in this race also vary from 3'4 to 3'6 inches; in length of bill, tarsi, and tail, a certain amount of difference is observable amongst individuals of both races but none between the two as a body.
