112 



are paler anteriorly, as are the toes, and the claws are hair-brown, margined with 

 whiteish. 



At the first autumnal moult, which takes place in September, the young 

 assume nearly the appearance of the adults : the fore-neck becomes white, the 

 breast dusky, with more or less red, and the head brown ; but it is not until the 

 second change that the colours are completed. 



Several curious circumstances are observed with respect to the bill of the 

 Dipper. In the first place, when the bird is young, it precisely resembles that of 

 the genus Turdus, being merely a little more slender ; but when the bird is 

 advanced in age, it is not merely proportionally, but actually much shorter, and 

 the tips, by being rubbed, become similar to those of the bill of the Woodpeckers, 

 although less neatly wedged. In this respect, the Dipper resembles the Oyster- 

 catcher ; and the change in the form of the bill is caused by the same action in 

 both species. Again, in old birds, the thin edges of the mandibles become marked 

 with parallel cuts, similar to those of the mandibles of the Gannet, although gene- 

 rally perpendicular, as in the Jabiru. 



The Dipper, which in the form of its bill and feet, and in the structure of its 

 digestive organs, is allied to the Thrushes, Pittae, and Chamaezae, is singular in 

 respect to its plumage, which is in a great measure that of an aquatic bird. The 

 parts of the body which in these birds are bare of down, are in it closely covered ; 

 bristles are entirely wanting at the base of the bill ; the feathers on the fore part 

 of the head are very short ; the wings and tail are also short ; and the body being 

 nearly as broad as deep, the adaption for floating and diving is obvious, although 

 the feet are not webbed, and the claws rather large, compressed, and curved. 

 These latter circumstances shew that the bird is not fitted for pursuing fishes 

 under water ; and, as I have remarked, although authors conjecture that fish 

 forms part of its food, none of them assert that they know this to be the case from 

 actual observation. 



The digestive organs are entirely analogous to those of the Thrushes, and 

 other allied genera, but bear no resemblance to those of the piscivorous birds, 

 the oesophagus being narrow and the stomach a true gizzard. The bird is destin- 

 ed to feed upon aquatic insects and mollusca, which adhere to the stones under 

 the water. It is, therefore, fitted for making its way to the bottom at small 

 depths, and maintaining itself there for a short time — a minute or more ; in con- 

 formity with which design, its plumage is short and dense, its tail short, its wings 

 short, broad, and strong, its bill unincumbered by bristles and of the proper form 

 for seizing small objects. Having its feet constructed like those of a Thrush, but 

 proportionally stronger, the Dipper thus forms a connecting link between the 

 slender-billed passerine birds and the diving palmipedes, as the Kingfisher seems 

 to unite them with the plunging birds of the same order, or perhaps with the 

 Herons. 



