260 [April, 



ning to make up my miud that I had before me a widely distinct 

 genus, I took up the sixth specimen, and then the seventh, both had I jii, 

 five sub-costal branches ; I next examined N'. capensis, five ; three i do 

 unnamed species, five again ; N. Buq^uetii, five ; N. j^gia, five. It thus 

 becomes evident that five out of our seven specimens of JSF. aralica 

 ought to be referred to Division 2 of my Kevision, and the remaining 

 two to Division 3, or, in other words, if neuration be arbitrarily 

 adhered to, that there exist two widely distinct genera in the indi- 

 viduals of one and the same species, and that the aberrant character 

 is the prevalent one in this species. 



Once more, knowing that a prevalent variation is likely to become 

 (by interbreeding) the normal one, there can be little doubt that in a 

 comparatively short time N. arabica, instead of being, as its describer 

 supposed, a mere variety of N. Buquetii, will be a widely distinct 

 genus, and one that may even, at some future period, be regarded as k 

 a mimic of its common ancestor. C 



British Museum : 



February, 1886. 



DESCRIPTION OF THE LARYA OF SCO PARI A MERCURELLA. 

 BY G. T. PORRITT, F,L.S. 



On the 14th of April last, I received from Mr. W. H. B. Fletcher, 

 of Worthing, a box containing mosses, in which were feeding (living 

 in silken galleries) a number of Scoparia larvae, but of what species 

 Mr. Fletcher was uncertain. The mosses I submitted to my friend 

 Mr. C. P. Hobkirk, who named them Isothecium myurum, and Hypnum 

 cupressiforme^ var. elatum ; and at the end of July and beginning of 

 August a beautifully marked series of Scoparia mercurella was pro- 

 duced from the larvae. 



On April 16th, I described the larvae as follows : — 



Length, about half to five-eighths of an inch, and moderately stout ; head 

 polished, the lobes rounded, it is scarcely so wide as the frontal plate, and still 

 narrower than the 3rd segment ; body cylindrical, and of almost uniform width, 

 tapering only a little at the posterior extremity ; segmental divisions deeply cut j 

 skin smooth, and slightly glossy ; the frontal and small anal plate, with the large 

 round tubercles, polished. 



In adult specimens, the ground-colour is a dingy straw-colour, but in young 

 examples it is strongly suffused with a darker dirty greenish tinge, which dark 

 colour seems to be gradually lost as the larva attains maturity. Head dark brown, 

 with frontal streak and mandibles still darker sienna-brown ; frontal plate very dark 



