Page - 454 - in The Origin of Species

454 ORIGIN OF SPECIES tance, "like that of all their parts, not only in this, but, as I apprehend, in every natural family, is very unequal, and in some cases seems to be entirely lost." Again, in another work he says, the genera of the Connaracese "differ in having one or more ovaria, in the existence or absence of albumen, in the imbricate or valvular sestivation. Any one of these characters singly is frequently of more than generic impor- tance, though here even vi^hen all taken together they appear insufficient to separate Cnestis from Connarus." To give an example amongst insects : in one great division of the Hy- menoptera, the antennae, as Westwood has remarked, are most constant in structure ; in another division they differ much, and the differences are of quite subordinate value in classification; yet no one will say that the antennae in these two divisions of the same order are of unequal physiological importance. Any number of instances could be given of the varying importance for classification of the same important organ within the same group of beings. Again, no one will say that rudimentary or atrophied or- gans are of high physiological or vital importance; yet, un- doubtedly, organs in this condition are often of much value in classification. No one will dispute that the rudimentary teeth in the upper jaws of young ruminants, and certain rudimentary bones of the leg, are highly serviceable in ex- hibiting the close affinity between ruminants and pachyderms. Robert Brown has strongly insisted on the fact that the posi- tion of the rudimentary florets is 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 physio- logical importance, but which are universally admitted as highly serviceable in the definition of whole groups. For in- stance, 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 inflec- tion of the angle of the lower jaw in Marsupials—the man- ner 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