(UO [December 



o-lasses, neither Baron Osten Sacken nor myself can discover any dis- 

 tinctions whatever between them, have yet retained these infinite- 

 simally minute distinctive characters unchanged and unimpaired for 

 5,0U0 or 50,000 or 500,000 years, or whatever other Hmit we may 

 choose to assign to the present Geological era. I could as soon believe 

 that it is possible, by the most unremitting attention, to propagate the 

 same breed of cattle, without losing or in any wise changing a single 

 point that characterizes the breed, for lOOO years ; whereas we know 

 that it is practically impossible to do this even for 30 or 40 years. 



If, indeed, we only met with these Colorational and Phytophagic 

 Unities in one geographical district, we might suppose them to be 

 caused by some peculiarities of climate. But go where you will, the 

 same universal laws follow you. The Cyni.ps of Europe, like their 

 American congeners, inhabit the Oak and not the Rose, and the Rho- 

 dites of Europe, like the Rhodites of the U. S., are found exclusively 

 on the Rose and never on the Oak. The Gomphwi from Japan and 

 the Gomphus from the Kurile Islands have the same yellowish ground- 

 color, and the same black stripes on the thorax, as the Gomp/ius of North 

 America and the Gomphiis of Europe. The Ciclndela from Hindostan, 

 80 far as regards the elaborate pattern traced on its elytra, is as like as 

 two peas to the Ciclndela of the United States and the Glcladda of 

 England. And the same law holds good on both sides of the Atlantic, 

 as regards both the coloration and the food-plant of Pontui. and Ple.rl.t, 

 and Collas, and Argijnnls. and Hlpparrhla. 



These illustrations might be indefinitely prolonged; but every natu- 

 ralist can supply the deficiency from facts which have come under his 

 own observation, and I only refer to them here because they have 

 scarcely been touched upon in Darwin's great work. The absolute 

 identity in the imago state of several distinct species of Cecldomj/ui, as 

 shown in this Paper — the absolute identity in the imago state of two 

 distinct species of Halesldota, which I have demonstrated in a preceding 

 Paper — the Colorational Unity so especially remarkable in Insecta, 

 where we have so large a number of species to generalize upon — the 

 Phytophagic Unity of very many genera of Insects — like myriads 

 of other facts enumerated in the Origin of Species, all cry out with 

 one voice, that species are connected by a genetic bond — that they 

 were not independently created, but derived by gradual modification 



