50 



Mr. Capper's Zygcpua, described by Barrett (" E. M. M./' 1895 

 p. 219), with a fore-wing instead of a hind-wing, has the abnormahty 

 on the left side, as Tutt has observed to be usual as to wing abnor- 

 malities in tliis group. 



This would be an example of homa'osis, which I take to be, not an 

 abnormal development of the right thing, but a normal development 

 of the wrong thing, resulting from an amnesia on the part of the germ- 

 plasm of its proper action that I have outlined in referring to Mr. 

 McLachlan's cross-winged dragonfly. 



A specimen of Anthrocera trifolii, figured by Mr. South in the 

 "Entomologist" for September, 1894, may be instructive from this 

 point of view. The specimen appears to have no appendages on 

 the metathorax except one wing, which is a fore-wing, instead of a 

 hind-wing as it ought to be. I say may he instructive in this connec- 

 tion, since so far as we know, tlie missing legs may be the interme- 

 diate, or the posterior pair, and if the latter, have not improbably 

 been purposely removed from the specimen. If they were the pos- 

 terior legs, then their absence from the same segment as the missing 

 left hind- wing would imply some extensive injury to the larva com- 

 pletely destroying these legs, including their centres of regenera- 

 tion and the left wing disc. The right hind-wing disc would then 

 be left without some of its best data for orientation, without its 

 normal environment, and free to develop irregularly, and the ten- 

 dency, apart from compulsion otherwise, of germinal material to 

 develop into a fore- rather than into a hind-wing, would assert 

 itself. 



This prepotence of fore-wing tendency is seen in the many 

 instances in which the hind-wing has fore-wing markings, of which a 

 magnificent instance in Erebia goanfe, as well as a less pronounced 

 specimen of the same species, was lost in a memorable catastrophe 

 that happened to the collections of Mr. Tutt and myself made in the 

 Val d'Anniviers in 1899 (though these specimens were more notable 

 in having underside markings on the upper surface). 



Hind-wing markings on the fore-wing must be much rarer : I 

 cannot remember seeing or hearing of one. 



I am indebted to the Rev. C. R. N. Burrows for the opportunity 

 of examining and describing a teratological specimen of surpassing 

 interest. It is one that has not hitherto, so far as I know, been met 

 with, or, indeed, has anything at all similar been recorded. It cannot, 

 therefore, be classified with any of the other malformations I have 

 referred to (PI. II). 



It is a specimen of Acronycta fridens, a male, in which all the 

 genital appendages are in the interior of the abdomen instead of in 

 their usual situation. The terminal segments of the specimen con- 

 sist of the girdle or ring of the ninth segment, precisely as seen in a 

 normal specimen, except that the saccus looks larger than usual, 

 owing to the two sides of the ring, where the clasps are usually 

 attached, falling together in the middle line. The tenth segment 



