136 



Inheritance in Philosamia Hybrids 



F. ricini differs from P. cynthia in the absence of the mid-dorsal, 

 upper lateral and spiracular series of spots. I bred a number of the 

 wild P. ricini and found that the lower lateral spots varied considerably — 

 there was every condition between two spots in each segment and none. 

 (Text-figure 1.) I did not inbreed the ricini, hence do not know whether, 



M.D.Sp. 



Fig. 1. Diagrammatic drawing of the second and third thoracic segments in P. cynthia. 



D.r. = Dorsal tubercle. 



I.)S?p.r. =Infra-spiracular tubercle. 



L.L.Sp. = IjOwei lateral spots. 



L.iS. =Leg spots. 



M.D.Sp. = Mid-dorsa,l spots. 



Sp. S"!). -- Spiracular spots. 

 T/i.r.^ Thoracic tubercle. 

 {7.L..<S'jj. = Upper lateral spots. 

 U.L. T. = Upper lateral tubercle. 



as regards this variation, there is or is not segregation within the 

 species. Lefroy(8) when describing P. ricini (Eri worm) gives two 

 types of adult larvae, spotted and plain. Mr Watson however believes 

 this is an impure race due to a former mixture with P. canningi (Hutton). 

 The description of the spotless larva suggests that it has no spots in 

 any position, but the statement made in reference to this point is not 



