V "s XI ] Steere, Distribution of Birds in the Philippines. 239 



twelve, in which each genus is represented by but a single 

 species in a place. This is about thirteen-fifteenths of the whole 

 number of genera and five-sevenths of the whole number of 

 species ; altogether too great a proportion of both to have no 

 significance. 



If we add to Lists B and C List D, there results one hundred 

 and forty-five genera out of one hundred and fifty, and three 

 hundred and two species out of three hundred and twelve, or 

 twenty-nine from every thirty of the genera and over thirty from 

 every thirty-one of the species so distributed in the islands that 

 no two species nearly enough allied to be put in the same section 

 or subgenus are found existing in the same island. These three 

 lists teach the same law of distribution, and the difficulty in 

 formulating it is not in thefiicts but in the necessary imperfection 

 of the terms used in measuring the values of the various natural 

 groups of animals. The fact that these natural groups vary in 

 value indefinitely makes it forever impossible to so measure them 

 by the fixed rule of species and genus that all men shall be 

 agreed. 



The law of distribution of non-migratory land birds of the 

 Philippines may be stated as follows : — 



The genus is represented by but a single species in a place. 

 Or, in more general terms, as follows : — 



No two species near enough alike structurally to be adapted 

 to the same conditions will occupy the same area. 



The varieties or subspecies of birds in the Philippines, 

 wherever observed, follow the same law of distribution as the 

 species; the varieties of a species, if any, each existing in neigh- 

 boring but distinct areas. The great Bronzed Pigeon, Carpo- 

 phaga cetiea, has the bronzed shading of the back much deeper in 

 the specimens from Basilan than in those from the central and 

 northern islands, while those from Paragua have the wings much 

 bluer in color. The Red Woodpecker, Chrysocolaptcs xantho- 

 cephalzis, from the central islands, has more red on the throat in 

 the bird from Masbate than in the one from Panay and Negros. 

 The Cockatoo and Racquet-tailed Parrot of Mindanao are deci- 

 dedly smaller than the same species in the other islands. Other 

 examples of the same kind are numerous, and there appears to be 

 a tendency in every species to form as many varieties as it 



