CHAEADEIUS. 



93 



Many of the Plovers are shore-birds ; some of them frequent the banks of rivers and 

 lakes, whilst others resemble the Coursers and the Lapwings in living on the plains, 

 especially during the breeding-season. 



The species belonging to the genus Charadrius may be conveniently arranged in three 

 subgeneric groups : — 



Phviales, or typical Plovers and Dotterels. 

 HiaticulcB, or Ringed Plovers. 

 jEgialopJdli, or Sand-Plovers. 



In dividing the genus Charadrius into subgeneric groups, it is important to ascertain 

 which characters are old, and which have been more recently acquired. The oldest 

 characters are presumably those which are common to both seasons, to both sexes, and to 

 young as well as to adult birds i. 



The black subterminal bar across the tail-feathers, and the white at the base of the 

 outer web of the innermost primaries, appear to be very old characters, common to some 

 allied genera, and wherever found always constant. 



The subgenus Pluvialis must be diagnosed as follows : — 



Charadrii having any one or two of the following characters : coloured axillaries ; a 

 hind toe ; a barred tail ; or a dark patch on the belly. 



The subgenus Hiaticula must be diagnosed as : — 



Charadrii having all the following characters : white axillaries ; no hind toe ; white 

 belly ; and a dark subterminal band across the tail. 



Local 

 distribution. 



Subgeneric 

 groups. 



Trust- 

 worthy 

 characters. 



Diagnosis of 

 subgenera. 



^ When young birds differ in the colour of their plumage from adults, it is generally supposed that they 

 more closely resemble some remote ancestor ; and in popular parlance they are said to " hark back to their 

 ancestors." Darwin (Origin of Species, 6th ed. p. 529) says that " from the many slight successive variations 

 having supervened in the several species at a not early age, and having been inherited at a. corresponding age, 

 the young will be left but little modified and will resemble each other much more closely than do the adults — 

 just as we have seen with the breeds of the Pigeon. "We may extend this view to widely distinct structures 

 and to whole classes." Thus it is supposed that the ancestral Spotted Woodpecker had a red crown, because 

 the young in first plumage of all the species of the genus Picus have red crowns, though this feature is retained 

 in the adult of only three or four of the species. It consequently happens that the young of nearly aUied 

 species differ less from each other than the adults of the same species do, inasmuch as the young of each 

 species hark back to the common ancestors of both. There are. however, some startling exceptions to this 

 rule. When I described Picus japonicus I had no idea how good a species it was. Now that the young in 

 first plumage have been received from Japan, it is found that they differ far more from the young of P. major 

 than the adults of the two species do. The young of our hirds have nearly uniform buffish-white underparts, 

 whilst those of the Japanese species are profusely streaked with black on the flanks, and more or less so on 

 the throat and breast. The young of P. numidicus and of P. major also differ more from each other than the 

 adults of the two species do, those of the former having much darker foreheads than those of the latter (this 

 difference is, however, grossly exaggerated in the plates of Dresser's ' Birds of Europe,' one being coloured much 

 too white and the other much too black). The young of P. syriacus and of P. major also differ more from 

 each other than the adults do, the former being j)rofusely marked with crimson on the upper breast, a 

 character of which traces only are found in rare instances in the latter, or in adult birds of either species. 



