HYLIOTA. 
231 
Let us, in conclusion, offer a few remarks on the 
more general results which the preceding investiga- 
tion tends to establish, while the facts are as yet 
fresh on the memory. I. We perceive that all 
natural sub-genera, as such, imitate, as it were, or 
represent one or other of the primary forms of 
nature, and that their variation is regulated by the 
same order of succession. The rasorial forms, for 
instance, is followed by the tenuirostral ; and this, 
again, by the Jissirostral. 2. -That this law of vari- 
ation is the same, also, which regulates the varia- 
tion of the species : one example of this we have 
already given in a sub-genus of quadrupeds, and in 
the sub-genus of Todus we have a second example 
in the class of birds. Lastly, we perceive that the 
r ank of any one of these types can only be known by 
analysis ; and then only when our materials are very 
ample. Hence arises the uncertainty respecting 
the rank of every type ; because, without the most 
refined analysis, it is impossible to determine whe- 
ther a bird is a specific or a sub-generic type of 
form. Let us now proceed to the fifth and last 
group of this family. The 
EURYLAMIN2E, or Bro'adbills, 
as before observed, constitute one of the primary 
divisions of this family. They are a most remark- 
able group of birds, whether we regard their ap- 
pearance, or the extreme interest which attaches to 
