PACKARD. TRANSFORMATIONS OF SATURNIAN MOTHS. 551 



the 8th abdominal segment nearly three times as thick as that on the 

 fith segment. All the tubercles bright red on the swollen base ; beyond, 

 turquoise-blue ; the short spinules black. Suranal plate, the side of the 

 anal legs, and the thoracic legs yellow. Mid-abdominal legs yellow, 

 black at base. 



There are two subdorsal rows of black spots, one on each side ; a black 

 baud on the front of each segment passes down to a point near the spira- 

 cles. The larvae vary in the amount of black on the body, some having 

 more, others less. 



The larva differs from Stage IV in the part of the tubercles above the 

 red swollen base being much thicker, the spinules shorter, and there are 

 no tubercles on the prothoracic segment, these being in the last stage 

 represented by black dots. 



The larva feeds on the wild cherry. 



This is an unusually conspicuous larva, and as usual in the group the 

 bright hues and spots may be regarded as warning colors, the insect 

 being protected by what are probably venomous spines. 



In its markings (the six dorsal black spots) and armature it closely 

 resembles Philosamia cynthia ; the tubercles are all large and of nearly 

 equal size and shape as in the 2d stage of P. cynthia. There is no such 

 inequality as is to be observed in the 3d stage of C. prometkea where the 

 I'd and 3d thoracic dorsal tubercles and that in the middle of the 8th 

 abdominal segment are three times as large as all the other dorsal 

 abdominal ones. 



Judging by the larval characters Philosamia cynthia is a more primi- 

 tive or generalized form than Callosamia, since Philosamia retains the 

 equality in the size and shape of the tubercles all through its larval life. 



( '. calleta up to the end of Stage III is really nearer to Philosamia 

 than the genus to which it is generally referred, and this suggests that 

 phylogenetically Philosamia is the older genus, and that from it directly 

 sprang the species of Callosamia; C. calleta being the oldest species. 



Mode of casting its skin. — Before moulting the abdominal legs are 

 folded together and the crown or rings of both are contracted. 



One was seen in the act of ecdysis ; the skin had split open at various 

 places from one end of the body to the other. The thoracic legs become 

 free or are drawn out of the old skin before the head is cast off. 



