Vol 



" 'J Degen, New Species of Australian Magpies. 203 



from the figure of the head of the specimen of G. tibicen, the 

 latter being in the prime condition of adult plumage. 



Where, as happens in this case, the feathers of that portion of 

 the nape which are black overlie the white ones, owing to this 

 wear, which is greater at the tips, they being the most exposed 

 parts, they lay bare a much greater area of the white feathers, 

 which are white to their roots. Allowance also is required for 

 the shifting and the displacement of whole sets of feathers in a 

 specimen whose skin is dried only to serve for ordinary purposes, 

 having myself frequently found some portions getting quite out 

 of sight, others, perhaps, being made unduly prominent. Where, 

 therefore, the leading characters for specification in a genus 

 depend mainly on the relative distribution of only two colours, 

 such as black and white, as in this case, too much stress should 

 not be laid on the accuracy derived from surface-measurements 

 taken on these portions and such as the black band on the 

 back, &c. 



The same remarks would apply to other parts in regard to 

 absolute measurements — for instance, lengths of bills and tarsi — 

 unless it were done only under positively analogous conditions. 

 A measurement such, for instance, as one taken over the culmen 

 of a bill may, with an equal amount of conscientiousness, become 

 either 2.3 in the hands of the one taxonomist, as it is liable to 

 become 2.15 inches in the hands of another, both being experts. 

 An additional inch on a man's nose certainly would make an 

 appreciable difference in his facial expression, but no one would 

 on this account alone dispute his right for considering himself 

 as belonging to the species Homo sapiens. To dilate any further 

 on the validity of measurements after the results obtained for 

 the individual fluctuations occurring in the lengths of their flight 

 and other feathers, from a series of specimens belonging to a 

 distinct species, and related elsewhere, seems futile, and the same 

 would hold good for the tails, or, to be more accurate, tail- 

 feathers. Such distinguishing characters as " tail is shorter," 

 to say the least of it, are conceptions more than elastic. For 

 example, I find that quite a number of tibicen have tails 

 whose lengths exceed 5.5 inches according to whether we measure 

 slack or full. Moreover, there is no sharply defined limit for the 

 insertion of the rectrices, and much depends on whether we 

 include the caudal vertebrae or not. 



The last point, and one having possibly more weight in the 

 determination of this new species, concerns the feathering of 

 the legs, or " thighs," which is stated to be " white" in this case 

 " for the upper half and inner sides " and " white with dark 

 brown for the lower half of the outer sides." In G. tibicen, too, 

 I find the inner sides clothed with white feathers, and several 

 amongst them are " noticeable " equally in regard to their lower 

 portion. 



On the whole, I do not think the separation of this Western , 

 form of G. tibicen as a distinct species a sufficiently and conclus- 



