524 PRACTICAL AND SCIENTIFIC ZOOLOGY. 
iS) 
rally used the term ‘normal in the same sense as we 
apply the word typical; but we have preferred the 
latter, throughout the whole of this work, as being more 
expressive. 
(393.) We shall now attempt another mode of ex- 
plaining the difference between typical and aberrant 
groups, which will bring the matter home to the most 
ordinary capacity. Let the reader suppose that each of 
his five fingers represents one of the five divisions of 
every circle. Let him further suppose the thumb and 
forefinger to represent the two typical groups, and the 
three others, the aberrant. The first, or typical groups, 
as before stated, are always the most perfect ; that is, 
they are distinguished by possessing more strength, 
and are endowed with greater qualifications or perfec- 
tions, than any others. Now, the thumb and the fore- 
finger are the most important to the human hand: 
consider for a moment the strength and security which 
is given by the thumb to every office which the hand 
performs: how weak would be our grasp, how unsteady 
our writing, how insecure our handling, if we were un- 
fortunately deprived of this member! The loss of any 
one, or even of any two, of our three last fingers would 
not subject us to half the inconvenience of the loss of the 
thumb. The forefinger is nearly as important: it acts 
more immediately in unison with the thumb, and is only 
inferior to it in strength and utility. It matters not 
whether this prevalent use of the forefinger is the result 
of habit; nor is it any argument against the assertion 
to urge, that a man who loses his forefinger, or even 
his thumb, may, nevertheless, acquire the power of 
doing almost every thing necessary with his remaining 
fingers. The first two were manifestly intended to be 
more used than the others; and a greater power, or, 
what is the same thing, a greater perfection, has conse- 
quently been given to them. So far, then, for an illus- 
tration of the two typical groups. ‘The aberrant groups 
are three: they always preserve a sufficient similarity 
to the two others to show their absolute connection 
