The Origin of the Markings of Caterpillars. 385 



fluctuation. That this process of extinction does 

 not proceed rapidly, but rather with extreme 

 slowness, is seen in the ontogeny of several species 

 of Deilephila, which retain the now meaningless 

 subdorsal line through a whole series of stages of 

 life. 



In another group of Sphinx-larvae with longitu- 

 dinal stripes, an eye-spot became developed inde- 

 pendently of the subdorsal line, in the position of 

 the caudal horn, which has here vanished with the 

 exception of a small knob-like swelling. This 

 character -which we now see perfected in Ptero- 

 gon (Enotherce undoubtedly serves as a means 

 of causing terror ; but whether the incipient stages 

 possessed the same significance, cannot be decided 

 in the isolated case offered by the one species of 

 the genus Pterogon possessing this marking. 



In a third group of longitudinally striped cater- 

 pillars, the younger genus Chcerocampa, eye-spots 

 were developed directly from portions of the 

 subdorsal line, at first only on the fourth and fifth 

 segments. It can be here positively asserted that 

 this character served as a means of alarm from its 

 very commencement. It is certainly for this reason 

 that we see the subdorsal line in the immediate 

 neighbourhood of the spots disappear at an early 

 stage, whilst it is retained on the other segments 

 for a longer period. A portion of the younger 

 (tropical) species of this group then developed 

 similar, or nearly similar, ocelli on the remaining 



c c 



