1887.] 107 



In 1878 Mr. Mooi*e made a critical examination of the structure 

 of the Lithosiidce, the result of which proved that nearly every British 

 Litlwsia belonged structurally to a distinct genus. In his revision of 

 the Family he referred to his genus CoUita the L. griseola, L. compla- 

 nula, and Z. stramineola of Europe ; he does not, however, account 

 for L. complana. 



Lithosia complana is the true type of the genus Lithosia, and, so 

 far as I know, it has hitherto been only distinguished from L. compla- 

 nula = lurideola by a character so slight, that in the case of any other 

 species of any other group, it would have been scorned universally as 

 beneath notice, viz. : — 



1 — yellow costal stripe of equal width to hind margin L. complana. 



2 — costal stripe attenuated to a point at the tip L. lurideola. 



Von Heinemann, however, adds that in lurideola the costa ia 

 evenly arched, the collar only yellow in front and at the sides, and the 

 body and fore-wings are of a darker grey. 



To attempt to follow the above distinctions has proved a hopeless 

 task, uot only to Prof. Zeller, but I believe to every one who has 

 attempted to separate his species by them. 



Following Mr. Moore, and accepting neuration as a guide in the 

 separation of the European species, I find that ColJita lurideola, 

 griseola, var. stramineola, and its dwarfed form cycladum, Zeller, are 

 characterized by very simple neuration, there being no false or post- 

 discoidal cell in the primaries ; in Lithosia complana, however, this 

 cell is always present and usually very prominent, being visible in 

 many specimens without the use of benzine. 



With regard to colour characters, although all specimens of C. 

 lurideola have the " costal stripe attenuated to a point at the tip," 

 about half the specimens of L. complana in Prof. Zeller's collection 

 (some of which wei-e under each species) have the same character, 

 whilst others are intermediate between the attenuated and non- 

 attenuated types. 



Neuration is not always strictly constant ; but surely any struc- 

 tural character is more satisfactory than the extremely slight and 

 variable colour distinctions hitherto pointed out for the separation of 

 L. complana and lurideola. 



British Museum : 



July, 1887. 



