Phyletic Parallelism in Metanwrphic Species. 473 



firmly attached than to be able to run rapidly. It 

 is unnecessary for them to seek long for their food, 

 as they generally find themselves amidst an abun- 

 dance, and upon this depends the small develop- 

 ment of their eyes and other organs of sense. On 

 the whole caterpillars live under very uniform 

 conditions, although these may vary in manifold 

 details. 



The greatest difference in the mode of life 

 which occurs amongst Lepidopterous larvae is 

 shown by wood feeders. But even these, which 

 by their constant exclusion from light, the hard- 

 ness of their food, their confinement within narrow 

 hard-walled galleries, and by the peculiar kind of 

 movement necessitated by these galleries, are so 

 differently situated in many particulars to those 

 larvae which live openly on plants, have not ex- 

 perienced any general change in the typical con- 

 formation of the body by adaptation to these con- 

 ditions of life. These larvse, which, as has already 

 been mentioned, belong to the most diverse 

 families, are more or less colourless and flattened, 

 and have very strong jaws and small feet ; but in 

 none of them do we find a smaller number of 

 segments, or any disappearance, or important 

 transformation of the typical limbs ; they all with- 

 out exception possess sixteen legs, like the other 

 larvae excepting the Geometrce. 



Now if even under the most widely diverging 

 conditions of life adaptation of form is produced by 



