Vol. XXII. 



1923 



1 R()P.B:RTS, Birds of the Cramte Belt 299 



adaptive. A bird with the habits of Chrysorrlious has large feet 

 and stout legs, to enable him to hop about the ground, and a short 

 tail, so that he won't drag it, unless, indeed, he adopts the Wren's 

 dodge and cocks it. P>ut L'lncata has smaller feet and legs for 

 grasping purposes, and a larger tail for balancing, and in regard 

 to the small grasping feet we would instance the fore-feet of the 

 monkey as analogous. And so it goes on ad uifinitiini! 



lUit it may be asked where does this virtual negation of all 

 these external features lead to? We would answer, it is simply 

 by its negative exaggeration our plea to take the bird in the 

 field as a whole, and to attach to this whole an importance at 

 least equal to that which is attached to the individual features 

 taken separately. Is it correct that the shapeless cabinet specimen 

 gives the only true picture, and that the bird in life on its native 

 heath, if examined with interest, will not add something? Em- 

 phatically no ! From this standpoint, then, we would place in a 

 pigeonhole of its own, Smicrornis, Fiisca, Albogularis, and 

 Chthonicola, and, presuming we knew no other, make a type of 

 each without indicating any inter-relationship or systematic 

 position. And we would place Lineata, Pusilla, Chrysorrlious, 

 and Regidoidcs together. They are diverse in habits of feeding, 

 song and nest-building, but this very diversity has a gradation 

 about it which cannot fail to impress. From the field-worker's 

 point of view they are divisible into species which feed and live 

 chiefly upon the ground and others. And this same is expressed 

 by systematists by differentiating them into two genera — 

 Geohasilcus and Acanthiza. The former includes Chrysorrhous 

 and Regidoides, and considering them for a moment as types dif- 

 fering from Acanthiza, it is interesting to glance at the differ- 

 ences and see how they work out. Take the Yellow-tailed Thorn- 

 bill from the point at which he is first seen feeding on the ground. 

 The shorter tail and stronger feet and legs have already been 

 referred to ; on taking flight he spreads his tail, and to show the 

 expo.sed rump, the tribe-mark, to his mates, presumably on the 

 ground, he drops the point of his tail and seems to fly slightly 

 erect. One way to counteract this fractional displacement would 

 be a fraction the greater wing area with the increase as far as 

 possible from the displaced part. What more natural than that 

 the tip of the wing should be produced by lengthening the second 

 primary, the first being beyond hope? 



If it is considered by the Check-list Committee that differentia- 

 tion is really called for, we will not for a moment question that 

 it is wise. And further, we recognise, and it is equally important, 

 that those interested in the bird world require, like England, 

 tranquillity in order to do good work; for many a promising 

 recruit retires before the wordy storm, and it is often the man of 

 limited scientific attainments who plunges into it. 



We would wish, however, that the spirit of those old English 

 Naturalists who chose the original names could always be with 



