MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 279 



RECAPITULATION OF THE MORE STRIKING FEATURES IN THE ONTOGENY OF CERURA. 



Congenital characters. 



(1) The larva liatelies with fully developed steniapoda, iudicatiug that the geiuis has 

 •descended with little modification from a form like Macrurocampa. 



(2) The prothoracic horns are longer, hetter developed than in the mature worm, showing 

 that in this respect also the genus has originated from the Hetei'ocampin£e. 



Acquired characters. 



(3) The head is smaller in proportion to the body Ihan usual, owing to the great width of the 

 jirothoracic segment. 



(4) The body is all brown above in the first stage, beginning to turn green in the second, and 

 in the third becoming nearly as in the last stage. Thus the colors are more diversified, with more 

 green in tbe fourth and fifth stages, rendering the now more exposed larva more adapted for 

 lirotection l)y tlie resemblance of its markings to the yellow and red spots on the green leaves of 

 its food plant, which appear early in autumn. 



(5) The dorsal humj) on the third tlioracic segment does not seem to appear until the last 

 ■stage. (Dr. Dyar, however, tells me that it appears in C. multiscripta in stage III.) 



(6) The fihimental legs retain their shape from the first to the last stage, but if anytliiug are 

 a little shorter in the last. On the other hand, the spinules in the third stage become larger on 

 the underside than before, the filaments being held curved up more than before, so that the 

 defensive spines on the underside, in response to external stimuli, have developed more* ra]iidly 

 than those on the upper side. 



(7) Novel structures are the very long and well- developed supraanal plate and the pair of 

 •coi>roliferous spines (or dungforks) arising from the paranal lobes, and availaltle for tossing away 

 ■the pellets of excrement. These seem to be peculiar to the genus in this family. 



