Nos. 2 & 3.] THE AUSTRAL AVIAN RECORD 39 



group these into a less number, though this is necessary, and 

 we conclude that only by means of utilising coloration can this 

 succeed. Again, coloration cannot be considered without study 

 of plumage changes, and recognition of variation in connection 

 with the evolution of coloration in different groups. This has 

 already been suggested in connection with the Turdidse, but 

 only in a preliminary and vague manner. The pterylosis and 

 development of the feathering in the nestling of Passerines 

 must be studied, especial attention being given to convergence. 

 It is possible that by this means we could determine a more 

 or less acceptable linear sequence, which at present is non- 

 existent. Thus, the sequence given hereafter is based upon 

 the fact that the Corvidse represent the highest degree, a very 

 debatable item. It may be suggested here that there can be 

 no family deserving of such distinction, as several families may 

 have developed equally, as in other groups, in different manners, 

 each of which would be equally representative of a high state 

 of development. Thus, one factor that has been put forward 

 is the uniform coloration of nestling and adult of both sexes ; 

 this can be seen evolving in one family alone, in which the 

 nestling to the male shows four plumage changes in one 

 species, and in another the intervening changes have lapsed 

 and the nestling takes on that of the adult almost in the first 

 plumage. Similarly, species with booted tarsi in the adult 

 show a scutellate acrotarsium in the nestling, and so forth. 



In the preparation of this scheme we have provided our own 

 conclusions without deference to any previous authorities. 

 Upon completion we contrasted it in detail with the better 

 known propositions and have been surprised to see that the 

 bulk of the groups coincide, and consequently very little 

 objection can be made to the majority. 



As to the fossil forms, we have not attempted to incorporate 

 these in this system, as the majority of them cannot be deter- 

 mined, and it is probable that most should be classed on a 

 distinct plane, as has been already suggested. To quote even 

 their names and the location suggested by systematists would 

 occupy a lot of space without much benefit. It will be noted 

 that in this prehminary survey we have not introduced a mass 



