30 L February, 



The Genus PEOSOPOPHORA. 



Mr. Maskell (vol. iv, p. 104) objects to " surface with gi|anular 

 raised lines " being considered to be a generic character of the scales 

 ( ^ and ? ), contending that it is only specific. In this case it may be 

 so J I do not wish to argue, all the more that Mr. Maskell says he has 

 two new species destitute of the raised lines which, ccdteris paribus, 

 will fit into the genus. It is very difficult in a new form to determine 

 which of its characters are generic, and which are specific. Other 

 species may exist in which, as in P. dendrohii, there may be raised 

 lines yet in a different pattern ; then the character would, I think, be 

 generic. We see in other Orders of insects some one leading struc- 

 tural character admitted to be of value in estimating generic rank, 

 while its variation in respect of pattern, density, complexity or other 

 quality, exemplified in a group of forms is held to indicate specific 

 difference, e. e., fixity for the time being in departure from a primitive 

 stem. 



153, Lewisham Road : 

 1893. 



LITHOCOLLETia TBIQUTTELLA, STN., A VARIETY OF 

 L. FAGINELLA, Z. 



BY EUSTACE E. BANKES, M.A., P.E.S. 



Lithocolletis triguttella was originally described, in the " Zoolo- 

 gist " for 1850, p. 2896, by the late Mr. H. T. Stainton from a single 

 specimen taken at Sanderstead in May by Mr. J, W. Douglas, but 

 from the following evidence I think it will be clear that it is nothing 

 more than a variety oifaginella, and that for the future the synonymy 

 should be : — Lithocolletis faginella, Zell., Stn., var. triguttella, Stn. 



Early in 1892, when, through the kindness of the present owner, 

 Mr. P. B. Mason, I was examining Mr. Douglas's collection, I made 

 an entry to the effect that the unique example of L. triguttella looked 

 to me in every respect like a genume faginella, ^ , except that, owing 

 either to the union of the typical third and fourth white costal streaks, 

 or to the absence of the fourth, while the third was unusually large, 

 there were only three such streaks instead of four. On reaching 

 home I examined for the first time a long series of faginella, bred in 

 the previous year from larvsD collected here, which showed that the 

 white streaks vary greatly in size and shape, and, to some extent, 

 in position ; one $ , entirely forgotten since it was set, was a veritable 

 " trigiottella,^'' for the third and fourth costal streaks had, on both 



