O. A. Merritt Hawkes 153 



• Summary. 



1. The plain or non-spotted condition of the larva of P. ricini is 

 recessive to the spotted condition of the larva of P. cyntlivi (Ning-po 

 variety). 



;: 2. The dominance in the F^ generation is incomplet.e ; all the larvae 

 are spotted but not all have the full complement of. spots. ■ 



3. " The spots are probably represented, not by one, but by a group 

 of related gens in the chromosome. 



• 4. The dominant homozygous and the heterozygous forms can bo 

 distinguished only by breeding, as both may be either full- or partly- 

 .spotted. 



5. A number of abnormal larvae with reduced tubercles occurred 

 in the F^ generation; when mated with normal larvae, this character 

 behaved as a recessive; whether it was a mutation which occurred de 

 novo as a result of this particular cross or whether it is a result always 

 to be expected from this hybrid, has not yet been determined. This non- 

 tubercled mutation (?) is interesting in relation to the few non-tubercled 

 species among the Saturniids. 



EXPLANATION OF PLATE VIII. 



figures A 1, A 2, A3, A 4 are larvae of F-i- 



A 1 — \ natural size. Normal tubercles. Full spots (S). 



A 2 — f natural size. No trace of tubercles. Full spots (S). 



A 3 — I natural size. Irregular tubercles. Full spots {S). 



A 4 — \ natural size. Slight vestiges ol tubercles. Reduced spots {RS). . 



Figures B 1, B2 are larvae of Fi and F.^ of the cross between a normal and an abnormal 

 larva. (See Table III.) 



B 1. — Natural size. Normal tubercles. Full spots (S). 



B 2. — Upper larva — 5 natural size. Traces of tubercles as chitinous rings. No spots (P). 

 Lower lafVa — J natural size. Normal tubercles. No spots (P). 

 i- igures C 1, C 2, C 3, C 4 are laivae of F-t, . They were blown by Mr J. W. Watson, f natural 

 size. 



C 1, C 2 are lateral and dorsal views of a nou-tubercled, full-spotted larva (S). 

 C3, C4 are lateral and dorsal views of a tubercled, plain (P) larva. This specimen 

 shows some spots of the lower lateral series on the abdominal legs..; The large 

 spots at the side are the spiracles. 



