56 Parker — On the Skeleton of Archeopteryx. 
In a very large proportion of typical perching and climbing 
birds, there are four joints thus clamped together behind the 
thigh-bones; in many of the walking and running land-birds 
five; whilst in the Swan, the Emeu, and the Diver ( Colymbus 
septentrionalis), there are as many as eleven. ‘Taking the 
average of the whole class, we shall find that the fifth post- 
femoral joint is—typically—the first caudal: and this agrees 
with Professor Owen’s determination in the case of the Ar- 
cheopteryx. 
This enumeration gives us twenty-one caudal vertebre for 
this remarkable creature; a number which, at first sight, 
appears very great as compared with what we see in existing 
birds. If, however, we examine the ‘ ploughshare-bone’ of a 
recently hatched Duckling, we shall find that it is composed of 
ten segments; and then, counting the fifth post-femoral as the 
first tail-bone, we get twenty-two as really belonging to that 
category. Following the same plan in other birds, especially 
amongst the Aves precoces, we shall, in many cases, get an 
equal result,-as many as twenty-four in the Swan, which, 
when young, has at least sixty-five vertebre in all. Iam not 
disposed to overrate the value of these remarks; yet it is well 
to be accurate even in detail; and itis highly interesting to see 
how little Nature has gone out of her way, after all, in the con- 
struction of this unlooked-for bird—the Archeopteryz. 
The general relationship of the Bird-class to the true (abran- 
chiate) Reptiles has still to be worked out; and it is difficult 
to say which Birds are the most reptilian. In some respects the 
Ostriches are, undoubtedly; and yet no living bird comes 
nearer the Mammal, in many important respects, than the 
Cassowary. 
The excellent qualities and high intelligence of the arboreal 
Birds would seem to set them at a great distance from the 
Reptiles; and yet the skull of the Crocodile comes very much 
nearer that of the Mammal than what is to be seen in any 
typical Bird. 
Moreover it is only in typical Birds (e. g. Turdus), that I 
have found any rudiment of that most characteristic lacertian 
bone, the pterygoidean columella; and in these very Birds the 
palatine transverse bone has its best development, a bone which 
is seen at its best in the Crocodilia, Lacertilia, and Ophidia: 
but which has no existence below these groups, nor above the 
Birds; and is either abortive, or quite absent in the greater 
number of birds having precocious young. ‘There is a curious 
blending of the characters of the various reptilian groups in the 
Birds; there has been no exclusive adoption of the mode of 
