i892.] THE BRITISH NATURALIST. 63 



is stunted. These are usually without the clouded costa and black 

 streak on the anterior lobe, but in some specimens both characters 

 appear indistinctly, and, in some few, they are to be seen pretty 

 distinctly ; in fact, the two forms distinctly overlap. I remember, 

 that at Ranworth Fen, a patch of very luxuriant Scabiosa siiccisa 

 produced specimens that leaned altogether to the plagiodactyhis form ; 

 while at Brandon, among Scabiosa columbaria and arvensis, the two 

 forms were so mingled that no one could separate them. Now, in all 

 these forms, the black spot before the fissure is constantly present. 

 It does not seem in the least degree to share in the inconstancy of the 

 other dark margins, and the white border of the fissure is also usually 

 visible. From the Lake District comes a form in which these reliable 

 characters are much as usual, but the variable characters — the 

 clouding and black streak - are so much exaggerated that the insect 

 has been described as a distinct species. It has, however, been 

 reared from precisely the same larvae to those of plagiodactyhis, feeding 

 in a precisely similar way. I have many times spent hours, with 

 good magnifiers, over long series of these various forms, and have not 

 been able to find any reliable point of distinction between them, and 

 the only logical conclusion I can come to, is, that they constitute but 

 one species — hipunctidactyla, of Haworth. As already stated, I believe 

 the few British specimens that have been reared under the name of 

 aridus, Z., to be pale ochreous varieties of this species. I will not 

 venture an opinion upon Zeller's aridus, of which I have but a single 

 type, and which is recorded from Southern Europe, Northern and 

 Western Russia, Armenia and Palestine." (" Ent. Mo. Mag.," Vol. 

 XVIII., p. 179). 



Some three years after Mr. Barrett had come to this satisfactory 

 conclusion (April, 1885), Mr. South writes: — "I am inclined to think 

 that MimcBseoptilus bipunctidactyla and plagiodactylus are only forms of 

 one species. I have a long series of both varieties from various parts 

 of England. Looking at the series of both as a whole, variation as 

 regards intensity of wing-marking and size of individuals is exhibited; 

 but the range of variation, as regards markings and colour, is not so 



THE DIPTERA OF DORSETSHIRE. 



BY C. W. DALE, F.E.S. 

 (Continued from Vol. /., p. 8^). 



Sub-order— APHANIPTERA. 



Family — Pulicidte. 



17. Ccratopliyllus assiiiiilis, Tach. On shrew mice and voles. 

 Introduced as a British species under the name of Typhlopsylla assiniilis 



