22 Mr. W.S. Mac eay on the Comparative Anatomy 
Birds, and the point of nearest approach made by Birds to 
Mammalia. 
In the discussion of these subjects I must not be expected to 
produce any original facts. This, indeed, would not answer my 
purpose ; since, in all similar questions, the instrument which is 
at once safest for the wielder, and most forcible against those for 
whom it is intended, is the argumentum ad verecundiam. 
First, as to the orders of Mammalia :—there is one to which we 
must all look with peculiar interest, as being that of which Man 
forms the type. Great as is the gulf between Man and the 
Ourang Outang, between the Bimana and Quadrumana of Cu- 
vier, it is impossible not to see, with Linnzeus, that they possess 
many characters in common*, and consequently impossible not 
to agree with him, that they form one group, which may be 
distinguished from all others by the general structure of their 
first by not carefully investigating the value of the analogies on record, and then by 
trusting to the theory of parallelism in preference to the less fallible guide of affinity, he 
has produced a series, which, in the conclusion, he himself discovers not to be valid. 
Whether the affinities of his minor groups be of superior value he does not enable us 
to judge, as no reasons whatever are given for them. ‘This mode of proceeding is 
the more to be regretted, from his evidently being conversant with the various forms 
of Mammalia, and from his having pointed out the orders in a very lucid manner; 
from which I have not failed to derive advantage. This much, I fear, cannot be said 
of the contents or affinities of these orders ; and therefore, as he has done me the honour 
of referring to my views of the subject (and his paper, indeed, purports to be a quinary 
distribution of the class), I may, perhaps, be allowed to express a hope that the ques- 
tion may be followed up. One thing is sure, that nothing can be easier than to make 
five groups, provided we do not conceive it necessary to prove them to be natural. 
Having, therefore, stated his propositions, he will be expected to prove them either by 
original observations of his own, or the recorded ones of others. At present his paper 
proves nothing, ascertains nothing; but leaves every affinity to be pointed out. I need 
scarcely say, that without some such proofs in detail of the connection between the 
component parts of the group, and thus of its unity, his propositions must remain 
dubious, and all new names without authority. 
* Amen. Acad. vol. v. p. 67 et seq. 
. 
skull, 
