304 THE ENTOMOLOGIST. 



I think, first mentioned in connection with P. atalanta ab. merri- 

 fieldi, Stdfss., bred in the year 1892 by Mr. Merritield for the 

 first time, and I will therefore call the ocellated aberrations, 

 resulting evidently from the influence of a cool season on already 

 the larval (and oval) stages — P. atalanta ab. merrifieldoides. The 

 duration of the pupal stage ranged from eight to twenty-seven 

 days. The aberration appeared in both broods. 



VALUE OF GENITALIA. 

 By F. N. Pierce, F.E.S. 



I AM glad to see that at last we have a distinguished entomo- 

 logist like the Eev. George Wheeler who has the courage to voice 

 what must be in the thoughts of every entomologist attempting 

 to decipher the weird photographs of genitalia that have lately 

 been appearing. 



First, illustrations in profile are utterly useless by themselves, 

 because in a vast number of cases the right and left sides differ — 

 that is, they are asymmetrical. Therefore, if anything like an 

 intelligent idea is to be obtained, the objects must be spread. 



There is no more difficulty in spreading the majority of 

 genitalia of the Lepidoptera so that anyone can understand and 

 compare them than there is in setting a moth or a butterfly. It 

 is impossible to imagine a collection of Lepidoptera pinned, 

 some vertically through the thorax, some horizontally, some 

 with wings folded over the body like a butterfly, others with 

 them lying close to the sides, &c. Can we imagine any but one 

 who has "made a long and very special study " of insects being 

 able to make head or tail of such a collection ? But we know 

 a properly set collection of insects can be compared, part for 

 part and point for point, until the minutest difference is easily 

 observable. Hence the incipient entomologist is first taught to 

 set decently. But this in students of genitalia seems to go for 

 nothing, so that it would seem as if the preparations were pur- 

 posely made to prevent people from understanding them. 



I cannot agree with Mr. Wheeler that no two people can 

 make their preparations quite alike, any more than that no two 

 individuals can set insects the same. Yet, if genitalia are pro- 

 perly spread, I am confident that neither Mr. Wheeler or anyone 

 else could distinguish any difference in the mount. Unlike the 

 wings of Lepidoptera, the parts of the genitalia are mostly fixed, 

 and are bound to lie at the same angle, and assume the same 

 position. 



The Elms, Dingle, Liverpool, Oct. 11th, 1910. 



