92 THE CANADIAN ENTOiMOLOGIST. 



flies, in the family and sub-family characters, have not changed in 800,000 

 years, how long time would be required to bring them out of the "common 

 stock" to the grade they had reached in the Eocene ? Perhaps the 

 advocates of leg classification can solve it. 



Mr. Darwin, in his fourth chapter, gives a diagram explaining his 

 views as to how varieties appeared, and how, from simple variation, genera 

 and families might come to be formed. Starting with several species of a 

 widely distributed genus, which resemble each other in unequal degrees, 

 he represents their offspring by divergent lines — the divergency in each 

 case showing the variation in the descendants of the original species. 

 Many variations appear in one or more of the groups, some of which go 

 but a little way ; others flourish, and in their turn give permanent varieties. 

 Some of the original species die out, and, at length, after many thousands 

 of generations, the surviving descendants of the original species are separ- 

 ated into distinct groups of unequal value, and which may be regarded as 

 families and sub-families. The branches, that is, the descendants of the 

 original species, do not evolve one from the other, but are all advancing in 

 their own way, unequally. That kind of evolution is intelligible, at least. 

 One group of butterflies, starting from the " common stock," whatever 

 that may have been, would come to have one manner of pupating, or its 

 bodily organs of a particular pattern ; another group a different manner 

 and pattern. The groups are not departing in every respect, or at all 

 equally from the parent form. No matter how far removed in time from 

 the parent, one feature or other may be retained through all the history. 

 Evidently, no such duration of time is required to bring the order of 

 butterflies to their present condition, as is called for by the other scheme 

 treated of Whether, of the several groups existing at any given period, 

 one were higher in the scale of existence than another, would depend, not 

 on the deformity of a pair of legs, nor the style of pupating, or the 

 papilla' on the tongue, or the presence of a ' tibial ephiphysis," but, in 

 the harmonious development of the whole organization. There can be 

 no ascending scale, because one family did not develop out of another, 

 but each separately, and according to the surrounding.* If there is a 

 highest family among the butterflies, as among mammals, the quadrumana, 



* There is no evidence whatever that a butterfly sprang from a moth, and it is a 

 fair proposition that all families of the Lepidoptera, diurnal, crepuscular, nocturnal, came 

 from a common parent, and were developing at same time, eacli in its own way. This 

 calls for vastly less time than the hshing-pole style of evolution. 



