RANK OF CIRCULAR GROUPS. 347 
sub-genus) and the species. That there is an inter- 
vening description of circles, however, between families 
and genera, has been so extensively demonstrated in 
ornithology that the matter has been set at rest, for it 
cannot be supposed for a moment that such groups 
should exist in, comparatively, so small a class as that 
of Aves, and yet not among true insects, whose numbers 
exceed those of birds, as much, probably, as in the pro- 
portion of twelve to one. Following our plan of giving 
examples, we may cite the divisions of the two families 
of shrikes and thrushes (418.) as so many sub-families, 
the genera there named being only typical examples. 
If the student wishes to see the demonstration of one 
of these sub-families, the Myotherine, or ant thrushes, 
he will find their analysis detailed at some length in 
“‘ Northern Zoology,” p. 168., and also that of the sub- 
family Piciane, or the pre-eminently typical wood- 
peckers, at p.300. of the same volume. Names desig- 
nating this description of group are made to terminate in 
-ine, as aready mark of distinction from such as, ending 
in -idx, indicate the names of families. 
(429.) We now come to Genera, of which more de- 
finitions have been given than of any other group in 
nature. It is quite unnecessary to repeat, in this place, 
the various and conflicting opinions of those who— by 
supposing there are no really definite groups in the cre- 
ation — affix to the term a meaning either so vague or 
so circumscribed as to leave every one at liberty to put 
their own interpretation upon the alleged definition. 
A genus, by the old writers, was the first assembling to- 
gether of species ; but no fixed rules were laid down for 
determining what degree of variation, among these spe- 
cies, would exclude them from being ranked under one 
generic name, or, if laid down, they were so frequently 
violated, that, in process of time, the original type seems 
to have been lost sight of, and a host of other species 
became associated with it, which frequently bore but a 
mere outward or remote resemblance thereto. Do what 
we will to define a genus,—or, in fact, any other 
