( ioi ) IV. On Specific and Mimetic Relationships in the gen/us Heliconius, L. By H. Eltringham, M.A., D.Sc, F.Z.S. [Read March 1st, 1916.] Plates XI-XVII. Some time has elapsed since Professor Poulton first suggested to me that an investigation into the specific relationships of the forms of the genus Heliconius would probably be productive of interesting results, and I must admit to having had some hesitation in embarking on such a work in view of the fact that a very lengthy and elaborate monograph of the genus already existed. This memoir, however, is based entirely on external characters, and it appeared that anatomical study might elucidate new facts with regard to the relationships of the forms, more especially as the mimetic phenomena are of an unusually complicated kind. Perhaps the most valuable feature of the monograph above referred to (Stichel and Riffarth, in " das Tierreich," 1905) is the recognition by Riffarth that the whole genus can be divided into two sections by means of a peculiar character of the fore-wing underside in the male. It was my friend, Mr. W. J. Kaye, who pointed out * that, having divided the forms by means of the character mentioned, a most remarkable fact was disclosed. A great number belonging to Section I resemble very closely forms belonging to Section II. In other words, intrageneric mimetic resemblance is of frequent occurrence I here use the words " mimetic " resemblance in a wide sense as indicating merely a similarity of pattern; the precise nature of the resemblance may be considered later. The present paper is an attempt to investigate more precisely the specific relationships of the forms of Helicon I us by means of anatomical study combined with an examina-tion of pattern gradations. AVe are rarely able in such investigations to arrive at entirely satisfactory conclusions owing to lack of adequate * True. Hut. Sue. Lend., p. xiv, 1907. TRANS. ENT. SOC. LOND. 1910. — PART I. (AUG.)
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