LINNEAN SOCIETY OF LONDON. 43 



between the forms are mueli commoner tbau on tlie adjaceut 

 mainland of Uganda where Mr. C. A. Wiggins has shown * that 

 the models are more abundant than the mimics. No reasonable 

 interpretation has been suggested except the one proi)osed by 

 Dr. Carpenter — that natural selection operates more stringently 

 in the preservation of the mimetic forms in one area than in the 

 other. Confirmation of a remarkable and striking kind has been 

 obtained by Mr. W. A. Lamborn t, who in 1913 bred from a 

 black-and-white liippocoon female of Papilio dcudaiais, captured 

 near Ibudan in S. K^igeria, the female offspring all of which are 

 represented in the accompanying plate I. Of the 15 male 

 offspring only a single one is shown (Fig. 2). Of the female 

 offspring 9 (Figs. 3-11) are seen to be Mjjpocoon like the 

 parent (Fig. 1), while 8 (Figs. 12-19) are the remarkable 

 form (Uonysus, well known but never common all along the 

 tropical West Coast of Africa. Dionysus exhibits a strange com- 

 bination of the patterns of certain mimetic females of dardanus 

 with features that are ancestral or reversionary. It is itself non- 

 mimetic, for the one rare Danaine (Amauris fenestrata) which is 

 something like it is only recorded from the Frduch Congo, And 

 just as Dr. Carpenter found that the mimetic forms varied away 

 from cheir models and ran into each other in the islands where 

 the models were few, so this single form, without a model, 

 varies in the localities where its sister-forms, with their models, 

 keep relatively constant. Dioiiysus has never been bred until 

 Mr. Lamborn reared the butterflies here represented, and proved 

 that this relationship holds even within the limits of the same 

 family. It is highly probable that the proportions are Mendelian 

 and the result of a recessive female parent mating with a hetero- 

 zygote male, and that all the hippocoou offspring are recessive 

 and all the dionijsus heterozygote, but this does not explain the 

 variability of the latter. Mr. C. F. M. Swynnerton has bred 

 families in S.E. Rhodesia which, on the same grounds J, are 

 probably made up of recessives and heterozygotes, but in all of 

 these except one all the female forms are mimetic and constant. 

 The single family which forms the exception includes like 

 Dr. Lamborn's a variable non-mimetic female form and a con- 

 stant mimetic one. 



The ancestral part of the pattern of dioni/sus is seen in the fore 

 wing, and the eight specimens have been arranged in the plate to 

 exhibit the gradual transition from Fig. 12 with its fore wing 

 resembling a liippocoon (Figs. 3-11) with the triangulnr white 

 patch of an unusually large size, to Fig. 19 with its fore wing 



* I. Congr. Internat. d'Ent. 1910, vol. ii. p. 483 ; also Froc. Ent. Soc. 

 Lo7id. ,1011, pp. xci-xcv. 



t Proc. Ent. Soc. Lond., 1914, pp. Ixiii-lxvi. See also pp. Ixvii-lxxi ; also 

 Bedrock, Apr. 1914, pp. 3(i, 37, 39. When this latter article was written tiie 

 whole family had not been received, so that the number of hijipocooii Is given 

 as (5 instead of 9. 



\ See Proc. Eut. Soc. Lond., 1914, pp. Ixviii-lxx ; see also pp. Ivi-Ixiii. 



