180 PROC. ENT. SOC. WASH., VOL. 23, NO. 8, NOVEMBER, 1921 



of divisions. These differences in themselves seem to indicate 

 that no homology exists between the adult and larva; however, 

 through a study of the transformation of the thorax of the pre- 

 pupa into the thorax of the pupa indications are found suggest- 

 ing the existence of a relation in development, or homology, 

 between the larval segmental elements and the adult segmental 

 elements. 



Metamorphosis (See drawings Plate XV, Figs. 9-10). 



The larva is ornamented on areas A, B, and C with prominent 

 black spots and when the larva sheds, the skin of the prepupa is 

 of the same shape but with the spots lacking color though rather 

 more prominent or elevated than in the larva. As the prepupa 

 develops these spots become more distinct, not in prominence, 

 however, for they lose to a considerable degree their elevation, 

 but in a difference of texture from the surrounding skin. In the 

 larva the skin of areas A, B, and C seems much the same in 

 thickness and rigidity, although perhaps the black shininess of 

 the spots does differentiate them rather markedly from the 

 surrounding tissue. In the prepupa as development advances 

 the skin between these spots seems to become considerably less 

 rigid and thick, and has somewhat the appearance of a mem- 

 brane connecting the toughened areas. As the pupa is formed 

 within, this membrane seems to occupy considerable of the sur- 

 face and enables the prepupal skin to accommodate itself to the 

 forming pupa. The spots seem to be in their relation to the 

 parts of the pupa formed below, the latent imaginal discs 1 from 

 which the adult form develops. 



The development of the prepupa is accompanied by two evi- 

 dent changes other than reduction in size and consequent 

 wrinkling of the skin. These changes are: the relaxing and 

 opening to some extent of the mandibles and a gradual move- 

 ment of the optical centers. The relaxing of the mandibles 

 occurs rather early in the prepupal stage and does not seem to 

 be especially indicative of the immediate approach of pupation. 

 The mandibles although open are capable of closing as was 

 determined by inserting objects between them. The movement 

 of the sensory parts of the eye is, however, considered of impor- 

 tance as indicating the beginning of the greater changes inciden- 

 tal to the development of the pupal stage. 



The prepupa up to the apparent beginning of the formation 

 of the pupa has a black eye in a black eyespot but when this stage 

 is attained the eye assumes a translucent whitish appearance 

 in the black eyespot. A close examination will now reveal that 

 the eye or the sensory part, is being withdrawn from the old 



'Korchelt Heider Text book on Embryology, Invertebrates, Part III, 

 Insecta, footnote p. 296 (Burger). 



