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XXIII. Xanthorhoe ferrugata (Clerck) and the Mendelian 

 Hypothesis. By Louis B. Prout, F.E.S. 



[Read December 5th, 1906.] 



About tea to twelve years ago, consequently some time 

 before I first made acquaintance with Mendel's theory, I 

 undertook some rather extensive heredity experiments 

 upon Xanthorhoe (Coremia) ferrugata, Clerck, generally 

 known to British entomologists as Coremia unidentaria. 

 Haw., a common little Geometrid species which exhibits 

 very definite colour dimorphism. A tolerably full account 

 of the results I obtained has already been published in 

 the "Transactions of the City of London Entomological 

 Society " for 1897-98, pp. 26-34, but as that periodical 

 has had but a limited circulation, and as, for obvious 

 reasons, I made no reference to the relation of the experi- 

 ments to the views of Mendel, I make no apology for 

 republishing the main outlines. 



The synonymy of this species and its closest relative, 

 X. spadicearia (Schiff.), Bkh. = ferrugaria, Haw., has 

 been much confused, and is almost unintelligible in most 

 of our catalogues, but will be found clearly set forth in 

 Meyrick's " Handbook of British Lepidoptera," p. 229. 

 The only fault there is that Meyrick omits to mention 

 that the purple-banded form is the " type " of both Clerck 

 and Linnaeus, and occurs (though sparingly) in Britain as 

 well as " abroad," while the black-banded form is the ab. 

 (et var.) itnidentaria of Haworth. For the purpose of 

 the present paper it will be sufficient to speak of the type 

 as " purple " and the aberration as " black," thus avoiding 

 any tax on the memory of those who may not be familiar 

 with the complexities of the sjmonymy. 



There is no doubt that, in Britain, the black is the 

 " dominant " form, in the ordinary acceptation of the word, 

 and without postulating any Mendelian application. I 

 have repeatedly bred from wild black females and have 

 invariably obtained therefrom black specimens only, some- 

 times carrying on the strain for two or three generations. 

 Many friends have had the same result, and so has the 



TRANS. ENT. SOC. LOND. 1906. — PART IV. (jAN. 1907) 



