The Origin of the Markings of Caterpillars. 185 



distinguished from all the other known species of 

 Chcerocampa by the absence of a caudal horn, a 

 distinct but very small one is nevertheless present 

 at this first stage, and is indeed retained through- 

 out the entire course of development, but does not 

 increase further in size, and thus gradually becomes 

 so small in proportion to the size of the caterpillar 

 that it may be entirely overlooked. 



The first moult takes places after 4 5 days. 



Second Stage. 



The blue-green coloration remains unchanged ; 

 but a somewhat darker green dorsal line becomes 

 apparent down the middle of the back (the dorsal 

 vessel ?), and the subdorsal line now becomes very 

 broad and pure white, being much more con- 

 spicuous than in any stage of C. Elpenor (Fig. 25). 

 The tapering of the three front segments occurs 

 at this stage, arid oblique, dark-green striations on 

 a lighter ground stand out distinctly on the spira- 

 cles. As with C. Elpenor, the first traces of the 

 future eye-spots appear during the second stage ; 

 not in the present case as a curvature of the 

 subdorsal line, but as a spot-like widening of the 

 latter, of a brighter white than the somewhat 

 greenish colour of the remainder of the line. 



Third Stage. 



After the second moult, the formation of the 

 dark " ground area " of the eye-spots commences by 



