472 Mr. W. P. Pyeraft on the 
mented areas, whether these form margins, bars, or spots. 
This appears to me the only explanation of the vagaries, of 
“abrasion.” ‘Restricting the meaning of the word to fair 
“ wear and tear,” this certainly would not follow so exaetly 
the boundary-lines of pale margins, serrations, and spots. 
And yet it is a common thing—especially among, small 
Asiatic Woodpeckers—to find feathers in which pale margims, 
indentations, and spots have been cut out as cleanly as if 
caten by a parasite which preyed on the unpigmented fibre 
only—the ‘abrasion’? apparently stopping directly the 
darker colouring is touched. 
XXIV.— On the Tail-feathers of the Grebes. 
By W. P. Pycrarr, F.Z.S. 
THouGH it is popularly supposed that, in addition to their 
many other peculiarities, Grebes are tail-less, it is very 
difficult to find any definite statements on the matter. 
References to this point, of a more or less general character, 
‘are, however, fairly numerous. And of these the following 
may serve as instances :— 
Dr. Sharpe, in the recent edition of the ‘ Naturalist’s 
Library’ (British Birds), says that the Grebes may be dis- 
tinguished, among other things, “ by their obsolete tail, which 
is not visible.” In Yarrell’s ‘ British Birds’ Grebes are said 
to have “no true tail.” Macgillivray writes: “ tail a slight ° 
tuft of minute downy feathers, scarcely distinguishable.” 
Mr. W. R. Ogilvie-Grant, in the ‘Guide to the Bird-Gallery 
of the British Museum,’ describes the tail as “ inconspicuous, 
being a mere tuft of downy plumes.” 
T have, unfortunately, been unable to make my ilivesti- 
gations on this subject as complete as I had hoped to do; 
and this is because I have had to content myself almost 
entirely with skins. Of fresh specimens, indeed, I have been 
able to examine only two examples. of the Dabchick (Tachy- 
baptes fluviatilis), one of which was kindly furnished ‘by 
Dr. P. L. Sclater. S 
