The Origin of the Markings of Caterpillars. 215 



I have never seen a caterpillar of Galii which 

 showed traces of the subdorsal line in the last 

 stage, nor have I ever met with one which 

 possessed a second row of " mirror " spots ; so that 

 retrogression or a sudden advance in development 

 does not appear to occur. 



Of the North African D. Mauritanica, which 

 likewise belongs to the Galii group, I have not 

 been able to obtain specimens or figures of the 

 younger stages. The adult caterpillar is very 

 similar to that of Euphorbice, but differs in the 

 absence of the second row of ring-spots. For 

 this reason it must be regarded as a retarded 

 form at an older stage of phyletic development. 



I now proceed to the Livornica group. 



DEILEPHILA LIVORNICA, ESPER. 



This, the only European species here to be 

 considered, possesses almost the same markings 

 as Galii in its fourth stage, i. e. y a subdorsal line 

 with interpolated ring-spots. The species is 

 known to be rare, and I have not been able to 

 obtain living specimens, but I have examined 

 several blown larvae, all of which agree in having 

 the ring-spots sharply distinct from the whitish 

 subdorsal line, so that the latter is thereby 

 interrupted. Figures of the adult larva are 

 given in the works of Hiibner, Boisduval, and 

 Duponchel. In most specimens the ground- 



