ON AN OVERLOOKED SPECIES OF REGULOIDES. 135 



Mergui, Tenasserim ; 1 specimen ; November. 

 Shillong, Assam; 3 specimens; October. 



All Brooks' breeding birds from Cashmere belong to the 

 brown-headed race. If the birds are distinct, then all his 

 eggs belong to that, and not to the true super ciliosus. 



The difficulty that I have felt in accepting the two birds as 

 distinct species, for I have long recognized the difference in 

 tone of colour in the Burmese birds, consists in my knowledge 

 of the great variation in this, that is produced by differences of 

 humidity in the tracts inhabited. 



Compare the North- West Provinces Pericrocotus hrevirostris, 

 Glaueidium brodiei, Syrnium nivicolum, with specimens of 

 the same species from Sikhim. The coloration is invariably 

 and conspicuously deeper in the latter. Take Pericrocotus 

 roseus from the dry North-West, and the same bird from 

 humid Tenasserim. Take Pericrocotus peregrinus from arid 

 Sindb, and the same bird from the moist slopes of the Assam- 

 boo Hills. Take Picus mahrattensis from dry Upper India, 

 and the same birds from below the ghats in Rutnaghiri. 



Great differences in rainfall sharply restrict the areas of 

 distribution of many species, while in the case of others possess- 

 ing greater adaptive capacity they greatly change the tone of 

 plumage. Look at all the pale Persian and Belooch forms. 



I might multiply instances indefinitely, but the thing is too 

 apparent. 



At the same time such changes, though common to a degree, 

 are by no means the rule. Numbers of species undergo no 

 such changes. Reguloides proregulus is, as Mr. Brooks remarks, 

 the same alike from Murree to Debrooghur, but then it must 

 be remarked that to the best of my belief this species is re- 

 stricted to a humid climate, and is never found in the drier 

 regions except as a bird of passage. But there are many of 

 whom this cannot be asserted, and whose colours seem un- 

 affected by climatic variations of this nature. 



Whether then the North-Western and Eastern forms of this 

 Peguloides shall be accepted as distinct species, is a mere matter 

 of opinion ; sometimes I have thought that they should be, as 

 indeed I have of the two extreme forms of Pericrocotus peregri- 

 nus ; but on the whole my present views incline the other way. 



Still when Crocopus chlorig aster, phcenicopterus and viridifrons, 

 Thamnobia cambaiensis and fidicata, and a score of other similar 

 pairs and trios are accepted as distinct species, no logical 

 grounds for rejecting these can be put forward, and as to my 

 mind all classification is to a great extent, as regards minor 

 details like this, a matter of convenience, it does not appear to 

 me to matter one iota whether these closely-affined forms 

 are regarded as species or races ; the only important point is 



