Apkil 1, 1898.] 



SCIENCE. 



437 



a higt place to the memoirs with which Dr. 

 F. A. Dixey has enriched oar ' Transac- 

 tions.' In 1894 he read before the Society 

 his elaborate paper 'On the Phylogeny of the 

 Pierinse as illustrated by their Wing-mark- 

 ings and Geographical Distribution,' and 

 took occasion to discuss the wide divergence 

 from the primitive or typical pattern of the 

 group caused by mimicry in such genera as 

 Euterpe, Pereute, Disinorphia, etc. Adopting 

 the Miillerian interpretation as expanded 

 by Meldola, he proceeded to offer the orig- 

 inal suggestion that, in the acquisition of 

 closer resemblance between two or more 

 protected forms, it was not necessary that 

 in every instance the process of adaptation 

 should lie solely in the imitation of one 

 particular form as model, but that there 

 might very well exist mutual convergence of 

 the forms concerned, thus accelerating the 

 attainment of the common beneficial re- 

 semblance. This ' reciprocal mimicry ' the 

 author further explained in a paper read in 

 1896 ' On the Relation of Mimetic Patterns 

 to the Original Form ' (pp. 72-75), by a con- 

 sideration of certain mimetic sets of Heli- 

 conii, Pierinse and Papilioninse, which pre- 

 sent features and relations of pattern and 

 coloring explicable apparently in no other 

 waj"- than by the hypothesis in question. 

 This paper also gave a lucid demonstration, 

 traced through corresponding series of ex- 

 isting forms of both mimetic and non-mi- 

 metic Pierinse, of "the successive steps 

 through which a complicated and practi- 

 cally perfect mimetic pattern could be 

 evolved in simple and easy stages from a 

 form presenting merely the ordinary aspect 

 of its own genus," and further adduced 

 reasons for holding that " it is not necessary 

 that the forms between which mimicry 

 originates should possess considerable initial 

 resemblance." In his latest memoir, 'Mi- 

 metic Attraction,' read on May 5th last,* 

 Dr. Dixey expanded a suggestion that he 

 ^Trans. Ent. Soc, Lond., 1897, p. 317. 



had previously (1896) made respecting 

 divergent members of an inedible group, to 

 point out — still from evidence in the Pierine 

 subfamily to which he has devoted so much 

 fruitful study — " how the process of gradual 

 assimilation starting from one given point 

 may take not one direction only, but several 

 divergent paths at the same time, " with the 

 result that a more or less intimate mimetic 

 relation was brought about with several 

 protected forms of quite different affinities, 

 though each connected in their coloring and 

 aspect with some group of distasteful asso- 

 ciates. He further set forth very fullj' the 

 distinction which exists between the mim- 

 icry of inedible by edible forms, which 

 could only be in one direction and was of 

 advantage to the mimicker alone, and the 

 assimilation among inedible forms them- 

 selves, where the mimetic attraction acts 

 reciprocally, to the advantage of all par- 

 ticipators. 



Another of our Fellows, Colonel C. Swin- 

 hoe, distinguished for his wide and intimate 

 knowledge of Oriental Lepidoptera, read 

 before the Linn £ean Society, in 1895, a most 

 interesting paper ' On Mimicry in Butter- 

 flies of the genus HypolimnasJ^ In this 

 memoir, as the author points out, a small 

 group of wide-ranging mimetic insects 

 is followed throughout its geographical 

 distribution ; and the process of mimetic 

 modification is traced through the female, 

 from the amazing instability of that sex of 

 H. bolina (local form) in the Fiji Islands, 

 where the male is stable and of the normal 

 ancestral pattern and coloring, to the oppo- 

 site extreme in Africa, where (with the ex- 

 ception of S. misippus) both sexes of the 

 known allied forms of the genus are equally 

 mimetic.f The singular contrast between 



*Linn. Soc. Journ. Zool., XXV., pp. 339-348. 



t It should be noted that in the African H. salmaeis 

 and the Malagasy S. dexithea the sexes are alike and 

 non-mimetic, and that therefore these species probably 

 most closely approximate to the primitive appearance 

 of the genus. 



