l dispute
that the rudimentary teeth in the upper jaws of young ruminants,
and certain rudimentary bones of the leg, are highly serviceable in
exhibiting the close affinity between Ruminants and Pachyderms. Robert
Brown has strongly insisted on the fact that the rudimentary florets are
of the highest importance in the classification of the Grasses.

Numerous instances could be given of characters derived from parts which
must be considered of very trifling physiological importance, but which
are universally admitted as highly serviceable in the definition of
whole groups. For instance, whether or not there is an open passage from
the nostrils to the mouth, the only character, according to Owen, which
absolutely distinguishes fishes and reptiles--the inflection of the
angle of the jaws in Marsupials--the manner in which the wings of
insects are folded--mere colour in certain Algae--mere pubescence on
parts of the flower in grasses--the nature of the dermal covering, as
hair or feathers, in the Vertebrata. If the Ornithorhynchus had been
covered with feathers instead of hair, this external and trifling
character would, I think, have been considered by naturalists as
important an aid in determining the degree of affinity of this strange
creature to birds and reptiles, as an approach in structure in any one
internal and important organ.

The importance, for classification, of trifling characters, mainly
depends on their being correlated with several other characters of more
or less importance. The value indeed of an aggregate of characters is
very evident in natural history. Hence, as has often been remarked, a
species may depart from its allies in several characters, both of high
physiological importance and of almost universal prevalence, and yet
leave us in no doubt where it should be ranked. Hence, also, it has been
found, that a classification founded on any single character,
however important that may be, has always failed; for no part of the
organisation is universally constant. The importance of an aggregate of
characters, even when none are important, alone explains, I think, that
saying of Linnaeus, that the characters do not give the genus, but
the genus gives the characters; for this saying seems founded on an
appreciation of many trifling points of resemblance, too slight to be
defined. Certain plants, belonging to the Malpighiaceae, bear perfect
and degraded flowers; in the latter, as A. de Jussieu has remark