576 Mr. C. Ingram on 
further knowledge, I will refrain from hazarding any opimion 
on the subject. The characters, however, appear to be 
pretty constant in members of the same genus, and it is not 
unreasonable to assume that they may ultimately prove of 
some small taxonomic value. With regard to the last- 
mentioned case, Mr. Pycraft is of the opinion that their 
object is to guide the parents when feeding their young in 
the partial obscurity of the nest. However true this may be 
of the white marks, it cannot, I think, explain the presence of 
the black spots in other species ; moreover, those possessing 
the latter usually breed in open and fairly light situations. I 
have found that when diurnal birds nest in holes or dark 
places their young are almost always endowed with excep- 
tionally big, wax-like enlargements at the gape of the mouth. 
These are doubtless there to guide the feeding parent, and 
other markings would therefore be unnecessary. Good 
examples of this may be seen in Cinclus, Parus, and 
Troglodytes. 
Of course, in the adult bird the tongue is modified in 
accordance with the kind of food taken and the methods used 
in procuring it ; consequently it may vary not a little in the 
different members of the same family—but usually only 
in minor details. This fact—coupled with the similarity 
that is often noticed in the tongues of birds widely separated 
but of similar habits—has led Mr. F. A. Lucas (‘ Auk,’ 
1896, pp. 109-115) to discredit the importance of this organ 
in classification. But the black tongue-marks are often so 
very characteristic and boldy defined that their presence and 
form may sometimes point to affinities where relationship 
has hitherto been obscure. Among European birds, so far as 
my observations go, this peculiarity is only observable in the 
young of some of the species possessing a thin and somewhat 
lorny tongue, like the Reed- Warblers, and is seldom found in 
conirostral birds with fleshy tongues. It occurs in the 
venera Hypolais, Acrocephalus, Locustella, Cisticola, Accentor, 
Panurus, and Alauda, while it is found in various degrees of 
intensity in Sylvia. In Motacilla it is sometimes only faintly 
indicated and almost obsolete; but I suspect that it is also 
