The Origin of the Markings of Caterpillars. 267 



less replaced by a brownish shade extending from 

 the back to the sides. Horn, black ; the upper 

 part of the first segment with a corneous plate, 

 similar to that of the Deilephila larvae. 



This stage is very variable, as shown by the 

 figures in various works. The variations arise on 

 the one hand from the struggle between the green 

 ground-colour and the reddish-brown extending 

 from above, and, on the other hand, from a more 

 or less complete disappearance of the associated 

 longitudinal lines. The latter are sometimes com- 

 pletely retained, this being the case in a caterpillar 

 figured by Hiibner (Sphinges, III., Legitimce,,\>), 

 where both the subdorsal and supra-spiracular lines 

 are continuous from segment n to segment i, 

 an instance which may perhaps be regarded as a 

 reversion to the primary form. 



The entire change of the marking from the 

 fourth to the fifth stage depends upon the fact that 

 the young larvae resemble the needles of the pine, 

 whilst the adults are adapted to the branches. I 

 shall return to this later. 



The ontogeny of A. Pinastri makes us ac- 

 quainted with three different forms of marking : 

 (i) simple coloration without marking; (2) a 

 marking composed of three pairs of parallel 

 longitudinal lines ; (3) a complicated marking, 

 arising from the breaking up of the last and the 

 addition of a darker dorsal line. 



Of the fourteen species placed by Gray in the 



