CHARACTERS OF THE DENTIROSTRES.' .947 
occasion,* we shall do so on this. It is a matter, 
however, of little importance, at what point the investi- 
gation of a circular group is commenced ; nor is there 
occasion to adhere implicitly to any fixed rule on the 
subject, provided that the subordinate groups are treated 
of in the same series as they are observed to follow each 
other in nature. 
(288.) Our survey of the Insessorial Order thus 
commences with the Dentirostres, or mpaeious tribe, 
whose prominent characters we have just noticed. The 
families of which this group is composed, with but one 
exceptiont, live almost exclusively upon insects, to se- 
cure which their bill is furnished with a distinct notch 
near the tip, assuming in the typical families the form of 
a prominent tooth. As a farther provision for procuring 
such sustenance, the angles of the mouth are more or less 
defended by stiff bristles, the legs are less robust than 
those of the typical perchers, and the claws are more 
acute. The bill is of various shapes in the different 
families. In the shrikes it is compressed ; while in the 
flycatchers, which lead immediately to the swallow tribe 
(^Fiseirostreii), it is much depressed, and the feet begin 
to be very small. 
(28g.) In detailing the characters of any comprehen- 
sive natural group, our attention must always be fixed 
more especially upon the typical examples of that group, 
and the characters it exhibits ; for, as the minor divi- 
sions branch off to the right and the left, and blend into 
other groups, it necessarily follows that these aberrant 
divisions lose many of the prominent features of their 
own type, and assume others more properly belonging 
to the next group. When, therefore, we say that the 
tribe before us is characterised by a strongly-toothed 
bill, by 'acute claws, &c., we speak only of its typical 
examples ; — the intelligent naturalist understanding that 
there are not only many exceptions, but that he will 
* Northern Zoologv, vol. if. 
t The Ampeiidtc^ tir berry-eaters, the types of which live more upon 
fruits. 
