2 1 8 Studies in the Theory of Descent. 



suppose either that this species is now in a state 

 of transition to a higher stage of phyletic develop- 

 ment, or else that the ring-spots were formerly more 

 strongly developed, and are now degenerating. 

 The developmental history of the larva could alone 

 decide which of these two views is correct. There 

 would be no difficulty in procuring materials for 

 this purpose if one of the numerous and zealous 

 Russian naturalists would take up the subject. 



DEILEPHILA HIPPOPHAES, ESPER. 



This is the only representative of the fifth and 

 oldest group known to me. The moth resembles 

 D. Euphorbia to the extent of being sometimes 

 confounded with it, a circumstance which is made 

 the more remarkable by the fact that the cater- 

 pillars are so completely different. 



The adult larva of this local moth has been 

 made known by the figures, more or less exact, in 

 the works of Htibner, Boisduval, and Duponchel. 

 Wilde also gives a description of it, although from 

 a foreign source. I will not here delay myself by 

 criticizing the different descriptions and figures ; 

 they are partly correct, partly inexact, and some- 

 times altogether erroneous ; they were of no avail 

 for the question which here primarily concerns us, 

 and new observation had to be undertaken. 



I have been able to compare altogether about 

 forty caterpillars, thirty-five of which were living. 

 All these specimens possessed nearly the same 



