STUDIES IN INHERITANCE IN THE HYBRID 

 PHILOSAMIA (ATTACUS) RICINI (BOISD) $ 

 xPHILOSAMIA CYNTHIA (DRURY) ?. 



By Mrs ONERA A. MERRITT HAWKES, M.Sc, B.Sc. 



Number I. ON LARVAL CHARACTERS. 

 (With Plate VIII and two text-figures.) 



Section I. On the Inheritance of Spots in the Larva. 



The larvae of P. ricini and P. cynthia are alike in general body colour 

 but differ from one another as regards the ribmber of black spots present 

 in the last instar. 



When an adult larva, P. cynthia has seven longitudinal series of black 

 spots, consisting, in all segments except the anal and cephalic, of two 

 mid-dorsal, two upper lateral, two or three spiracular and one or two 

 lower lateral spots. The upper lateral, spiracular and lower lateral are 

 arranged bisymmetricall3^ The spots of the lower lateral series occur 

 above the thoracic legs, on the abdominal legs and at a low level on the 

 legless segments. In the thoracic segments there is an extra spot on 

 each side at the base of the thoracic legs (Fig. 1). I have not been able 

 to breed P. cynthia (Drury) from Ning-po, so give this description from 

 the verbal statement of Mr J. W, Watson. Packard (9) gives a description 

 and figure of P. cynthia advena (Walkeri), the nearly related American 

 species, but does not mention the moth from Ning-po. Packard's descrip- 

 tion of P. cynthia advena would do perfectly for the Ning-po variety, 

 not only as regards spots but also in other details, but as I have 

 found the scales of the Ning-po cynthia considerably different fi'om 

 those of advena, and as they may differ considerably in genetic consti- 

 tution, it is possible that further observation may show an increasing 

 number of distinguishing points between the two. 



Jonrn. of Gen. vii 10 



