162 
CRIMSON NUT-CRACKER. 
their migratory hahits ; all which, as every one 
knows, are also the characteristics of the swallow 
family, and of all Fissirostral birds. Those, on the 
other hand, which represent the Tenuirostres have 
the longest hills ; and those, again, which typify the 
gallinaceous tribe, have the strongest feet and the 
shortest wings. All the species of Coccoborus , how- 
ever diversified in other respects, have a distinct 
notch (although small, and the tip not hooked, as 
in the tanagers) in the upper mandible ; and this, 
we all know, is the great distinction which separates 
the Dentirostres from the Conirostres. Numerous 
other analogies might he here pointed out, strength- 
ening the accuracy of the above arrangement ; but 
it is quite needless to proceed further. The clue 
being now given, the experienced ornithologist will 
be at no loss in following it up ; while the student 
will thus have an example he can comprehend, of 
that systematic order of variation in all animals 
which the discoveries of every year more and more 
demonstrate as the fundamental principle of the 
great plan of creation. "We now proceed to the 
genus Dertroides, the rasorial type of the hard-bills ; 
it contains at present but one known species, which 
is likewise of extreme rarity. 
