152 M. W. K. PARKER ON THE OSTEOLOGY 
exist between birds no further removed from the Reptilian groups than the Ostriches 
and the Rails; but I do contend that the possession of a compressed face and large 
inferior extremities by species in both these groups is not a sufficient reason for our 
marrying the two families into one. Do that, and all the family landmarks may with 
equal reason be obliterated,—a course which would, if followed out by some consistent 
painstaking ornithologist, result in the reduction of the great bird-class into one opulent 
family, possessed of a thousand genera and of ten thousand species. 
I shall speak hereafter of the typical (sylviine, or perhaps corvine) characters of 
Hemipodius, and of the strange build of certain Australian Sylviines (e. g. Petroica), 
birds with so mixed a constitution that the term Struthious Warblers would scarcely be 
inapplicable to them. I hope at some future time to take up this intricate part of 
ornithology, and, if possible, do something towards unravelling what appears, at first 
blush, to be so extremely confusing. It has for some time appeared to me that our 
so-called ‘‘ circles of affinity” should be made with toothed edges ; for the groups of 
birds do not merely impinge upon one another; they do more, they interdigitate. This 
dovetailing, as we all know well, occurs between class and class, as well as between 
order and order and between family and family. 
Thus the Batrachians are, as it were, only just lifting themselves up out of the Fish- 
class, and striving after the higher dignity of the crawling Reptile. The Ornithorhynchus 
and the Echidna have not quite freed themselves from the Reptilian group; whilst, in 
the structure of the face and the palate, the Crocodilians overlap the lower border of 
the Mammiferous circle, passing, in these respects, beyond what the Bird ever attains 
to, so that the Crocodilian skull is a prolepsis of that of the Mammal. At this sinuous 
border-line we fall in with the ‘‘ lot” of the Ostrich-tribe ; and from it we may pass in all 
directions through many a substruthious and many a subtypical group, until we come to 
birds with merry notes and perfect social economy. Wandering at will amongst these 
groups, it would appear that our only way of coming to some understanding about their 
proper arrangement will be to seize upon some well-known form as the convenient 
centre and type of each particular family. This practical type should stand fairly in the 
centre of several genera, the most unlike of which should impinge upon the outlying 
genera of the contiguous families. Our very best efforts at naturalness will often fail to 
make our family-groups of equal value; and the larger families will often have to be 
divided into a typical and one, two, or more subtypical families. The manner in which 
the families cluster round and overlap each other is extremely interesting ; this, how- 
ever, is often masked by the teleological modifications of certain important organs, 
especially the face and the pelvic extremities. 
Cuvier was wont, in his classification of birds, to lay hold on the modifications of the 
beak and the feet; but he seems to have been careless even of these organs in his 
nomenclature ; for he often named a group after some especial bird, as, for instance, his 
Orders ‘‘ Accipitres,” “‘ Passerine,”’ and ‘‘ Gallinacez,” which are his first, second, and 
