The Origin of the Markings of Caterpillars. 187 



it drew in the front segments, and expanded the 

 fourth (Fig. 28). The eye-spots of the fifth seg- 

 ment are much less developed than in C. Elpenor ; 

 they remain small, and are not readily detected. 

 On the other hand, there now appear on all the 

 segments with the exception of the last, just as in 

 the sixth stage of C. Elpenor, distinct rudiments of 

 eye-spots, which present the appearance of irregular, 

 roundish, black spots on the front borders of the 

 segments, at the height of the former subdorsal 

 line. In this latter region the black pigment is 

 disposed as a longitudinal streak, and to this a 

 median line is added, the whole forming a mark- 

 ing which perhaps makes the caterpillar appear 

 still more alarming to its foes. This marking is, 

 however, only to be distinctly recognized on the 

 three first segments. The " dorsal spots " men- 

 tioned in the case of C. Elpenor then appear very 

 distinctly on segments 5 n. 



The caterpillars continued to feed for eleven 

 days after the third moult, at the end of which 

 period the fourth moult took place, but without 

 the occurrence of any change of marking. The 

 larvae then buried themselves, the complete 

 development having taken 28 29 days. 



The development of the Porcellus caterpillar 

 was twice followed; in 1869 in twelve, and in 

 1874 in five specimens. In no case did I obtain 

 caterpillars which remained green throughout the 

 entire course of development, although this colour 



