THE YOUNG NATURALIST. 



By a printer's error on page 6, line 7, I am made to describe a variety of 

 Littorina littoreus as having te fine broad black bands/' it should have been 

 " five broad black bands." Probably the misprint was obvious to most 

 readers, but will those who have not before noticed it, kindly make the 

 necessary alteration in their copies ? 

 Cambridge. 



VARIATION IN LEPIDOPTERA. 



INTERMEDIATE FORMS. 



By JOHN E. ROBSON. 



It is always a pleasure to me when a subject, in which there is room for 

 difference of opinion, is taken up and debated in these pages. No scientific 

 question can be discussed in such a way without both sides learning more or 

 less from the other. In the various papers I have given to my readers dur- 

 iag the last six years, I have had two objects chiefly in view- — To tell the 

 facts I had learned, and to discuss the opinions I had formed. I have made 

 no claim, to be deeply learned in Entomological Science, but in a plain way 

 have endeavoured so to express myself that my younger readers would under- 

 stand me. Though I have written on Evolution, Reversion, and kindred 

 subjects, that are not perhaps understood by every one, I have always flat- 

 tered myself that I made myself intelligible even to Young Naturalists. It 

 is evident, however, that for once I have failed. My paper on " Intermediate 

 Forms," at page 209, of the last volume, has not been understood by every 

 one. Mr. Gregson's reply at page 25 1 is not the only communication I have 

 had on the subject, though the only one for publication. In replying to Mr. 

 Gregson I will endeavour to make it clear what I really meant ; yet I must 

 confess (if Mr. Gregson and my other critics will excuse me), I fail to see, 

 after carefully reading over my paper again, how I have been so much mis- 

 understood. 



Mr. Gregson says (p. 251) " I will write out a number of species from 

 my own knowledge, so that the readers may judge for themselves as to 

 whether there are species which produce intermediate varieties or not/' This 

 certainly implies that my argument was that intermediate forms did not exist, 

 whereas my point expressly was that there were intermediate forms, but that 

 in certain cases where there were " two well marked forms of an insect, 

 whether sexual or otherwise, the absence or rarity of intermediate forms 

 seems to require explanation." My arguments as to sexual variation Mr, 



