500 SHUFELDT. [Vot. III. 
I have said, that when the species now grouped in the genus 
Ciunicerthia come to be anatomically examined and carefully 
compared, they may show quite as much of the Tit in their 
organization as they do of the Wren. Indeed, they may stand 
directly between these two groups of birds, and the new C7zzz2- 
certhia described by Mr. Sharpe in the Catalogue of the British 
Museum, may prove to have far more of the Wren in it than 
has Cinnicerthia unibrunnea; or still more than C. wnzrufa. 
Our hard and fast lines in systematic classification are a little 
binding sometimes, and do not strictly define the delicate rela- 
tionships existing among such forms as go to make up the class 
Aves. 
CONCLUSIONS. 
It is only when one comes to investigate the morphology, in 
its entirety, of the smaller passerine birds, that it can in any way 
be appreciated how thickly the twigs stand upon that branch of 
the genealogical avian tree. As they have forked and split up, 
and been derived from each other, so have the bird forms which 
now represent this branching growth, become distinct in their 
thousand and one species, and in each we may look for inherited 
characters that likely they assumed and appropriated from a 
variety of ancestors at various stages of their derivation and off- 
shooting. Thus it is that we may come across a species of bird 
wherein the main trend of its morphology and organization is 
indubitably stamped with all the characters of the stock-branch, 
or that off-shoot where all those of its kind could be designated 
as clearly differentiated Passeres for instance, and yet it will 
show in different degrees tinctures in its make-up that have been 
borrowed by its economy from the earlier branchings that pre- 
ceded it. 
We may have a passerine bird presented to us, to offer an 
hypothetical case, which, to all intents and purposes, is in its 
entirety a representative of the great group which we have 
defined by that name. It may be the most fixed species of its 
genus, and yet when we come to study its structure in ad// its 
details, how puzzlingly do the anatomical evidences of its affinity 
crop up. So dilute may have some of the blood of remotely 
affined tribes run into itself that it lies quite beyond the power 
