224 Studies in the Theory of Descent. 



first segment. This also no longer forms the final 

 stage of the ontogeny, but is, however, undoubt- 

 edly retained in the second stage of several 

 species (D. Vespertilio, Livornica^ Lineata, and 

 perhaps also Galii}. 



Stage 3. The subdorsal line bears a ring-spot 

 on the penultimate segment ; the other markings 

 as in the last stage. D. Hippophaes only belongs 

 to this stage, a small number of specimens, how- 

 ever, showing a transition to the following stage 

 by the transference of ring-spots from the posterior 

 to the anterior segments. 



Stage 4. Open ring-spots appear on the sub- 

 dorsal line on all the segments from the eleventh 

 to the first. D. Zygophylli and the North 

 American D. Lineata belong here. 



Stage 5. Closed ring-spots are situated on the 

 subdorsal line. Of the known species, only D. 

 Livornica concludes its development at this phy- 

 letic stage. 



Stage 6. A single row of ring-spots replaces 

 the subdorsal line. D. Galii, Vespertilio, and 

 Mauritania represent this stage at the conclusion 

 of their ontogeny. 26 



Stage 7. A double row of ring-spots. Only 

 D. Dahlii, Euphorbice, and Niccea attain to this 

 highest stage of Deilephila marking, the two first 



26 [The caterpillar of Deilephila Euphorbiarum, figured by 

 Burmeister (Ldp. Re'p. Arg., PI. XVI, Fig. i) belongs to this 

 stage. R.M.] 



