A^ol. xxxvi.] 18 



Sylvidae aud Turdidae combined in the B. O. U. List), we get 

 almost every type of colour and marking. Sometimes in a 

 single species there is the most extraordinary variation, as in 

 thecaseoi Cisticola,Anthus trivialis, and Sylvia melanocephala. 

 We cannot, therefore, attach equal value to colour in all 

 cases. In some genera aud families it runs riot, in others 

 it is rigorously confined to one type ; but this furnishes no 

 reason for ignoring it. Anyone who takes the trouble to 

 study the structural characters by which the orders and 

 families of birds are differentiated; will see that they cannot 

 be used rigidly : what is crucial in one case is valueless in 

 another. In the Accipitres the beaks are all of one type, 

 but the bill of the Curlew is more like that of the Ibis than 

 the Avocet. 



In order to appreciate the value of oological charac- 

 ters let us see what they have taught us in the past. 

 Look back at the older works on ornithology, even as 

 recently as Yarrell's day, and see the wide gap between 

 the Laridae and the Limicolse : the close association of the 

 Procellariidae with the Laridse, with w'hich they were grouped 

 under one heading, the separation of the Charadriidse from 

 the Scolopacidse by the Gruidse aud Ardeidae I 



Since Fiirbriuger's day there has been a distinct tendency 

 to separate the Striges and Accipitres : the former being 

 classed with the Coraciiformes, and their apparent likeness 

 to the Accipitres being ascribed to parallel development 

 only. Certainly this derives some support from Oology. 

 The wide gap between the Ardeidae and the Gruidse is also 

 amply confirmed by the study of the eggs. 



That Ave have still much to learn has been shown quite 

 recently by Dr. P. E. Lowe in his study of the Chatham 

 Island Snipe, formerly ascribed to the genus Gallinago and 

 now shown to be a " living fossil," a survival from a far more 

 ancient stock. The difference between the eggs is so striking 

 that it arrests the eye at once. The eggs of G. gigantea 

 and G. stricklandi are Scolopacine, and it will be interesting 

 to see whether further studies of their anatomy will show 

 that they differ radically from Gallinago. 



In the B. O. U, List the orders Podicipediformes and 



