YOUNG BIRDS AND RECORDS OF THE PAST 139 



missed by his neglect to seek evidence of young birds ? 

 Briefly, he founded a system of classification on the form 

 and arrangement of the bones of the palate, whereof he 

 recognised certain distinct and sharply defined types, 

 without making the discovery that these were all modi- 

 fications of one common plan. That is to say, he appar- 

 ently regarded these several types as so many isolated 

 units, instead of so many divergent branches of a common 

 root. He realised, surely enough, that the palatal bones 

 of the adult members of the ostrich tribe presented a 

 more " generalised " condition than could be found among 

 the adults of any other birds, and thereby he seems to 

 have imagined a great gulf to be fixed between them. 

 Such a view, indeed, is well justified if one compares, 

 say, the palate of the skull of the emu with that of the 

 common fowl, or even the gull. But the early stages in 

 the development of these bones tell a very different story. 



In the case of the emu, which we will take as our standard 

 of comparison, it makes but little difference, it is curious 

 to remark, whether we examine the bones of the nestling 

 or the adult. It is curious because one would have 

 expected to find the skull of the young emu displaying 

 features characteristic of some distant past. But, be this 

 as it may, the particular facts to which we desire now 

 to draw attention concern the bones which, like rafters, 

 form the roof of the mouth. 



Turn for a moment to the figure illustrating the palate 

 of the emu. Note down the centre a long, broad plate 

 of bone, deeply cleft at its base to form a pair of outwardly 

 curved bars, which are attached to a pair of short, bowed, 

 flattened beams, pointed in front ; these are the pterygoids, 

 and the median plate attached thereto is the vomer : a 

 third element, which plays a very important part in this 



