The Colours of Animals. 103 



to explain. The young larva, in fact, represents 

 an old form, and the species, in the lapse of ages, 

 has gone through the stage which each individual 

 now passes through in a few weeks. Thus, the 

 caterpillar of Chcerocampa porcellus, a species very 

 nearly allied to the Elephant Hawk-moth, passes 

 through almost exactly the same stages as that spe- 

 cies. But it leaves the egg with a subdorsal line, 

 which the caterpillar of the Elephant Hawk-moth 

 does not acquire until after its first moult. No 

 one can doubt, however, that there was a time 

 when the new-born caterpillars of the small Ele- 

 phant Hawk-moth were plain green, like those of 

 the large one. Again, if we compare the mature 

 caterpillars of this group of hawk-moths, we shall 

 find there are some forms which never develop eye- 

 spots, but which, even when full grown, correspond 

 to the second stage of the Elephant Hawk-moth. 

 Here, then, we seem to have species still in the 

 stage which the Elephant Hawk-moth must have 

 passed through long ago. 



