CATALOGUE OF DIPTERA, &C. 147 



Art. XVII. — Catalogue of Diptera occurrhuf about Holy- 

 wood in Downshire. By A. H. Haliday, Esq., M. A. 



[to the editor of the entomological magazine.] 



Sir, — I send you a list of some Diptera occurring about 

 Holywood, in the county of Down. Should you think it not 

 unsuited to the pages of the Entomological Magazine, the 

 Notes appended will afford the necessary explanations of the 

 nomenclature adopted, where it differs from that of Meigen or 

 of the published British Catalogues. As I am aware that a 

 bai-e local catalogue may not seem of sufficient general interest 

 to occupy so many pages, I should probably not have thought 

 of it had time allowed me to offer any contribution of greater 

 labour and detail. Perhaps, however, as referring to a district 

 in this respect nearly unexplored, this list may afford some 

 hints for the advancement of our Insect Geography. I am 

 sorry therefore to present it in so meagre a form, many of the 

 most extensive genera being unexamined in detail. These are 

 indicated by the asterisk prefixed ; and some of them I have 

 thought it better to pass over entirely. Perhaps, however, 

 a few facts may be gleaned from it, such as it is. The total 

 absence of the families of Bomhylii and AsUi is observable ; 

 and, considered in connexion with the small proportion which 

 the British species bear to the European in the aggregate, 

 seems a result partially determining the law of progressive dis- 

 tribution among these forms. The disappearance or extreme 

 rarity of the finer genera (the Optimates) among the Tahani, 

 Stratlomydes, Syrphi, &c. may also be remarked, as well as 

 the absence of various conspicuous (and in this point of view 

 more insulated) groups, such as Ctenophora, Aspistes, Pa- 

 chygasier, Platypeza, Diaphorus, Echinomyia. Gymnosoma^ 

 Micropeza, Platy stoma, &c. On the other hand, the pre- 

 dominance of particular tribes may afford some indications ; 

 the Dolichojn, as a family, are pretty full (so also the minuter 

 Tipulidce, though not appearing from this catalogue) ; the 

 Muscidce, of less typical structure (all the genera after Cceno- 

 sia, or perhaps Scatojjhaga ?) are by no means scanty. A few 

 groups seem to approach their culminant point ; Ccelopa, a 

 genus unknown to the shores of the continent, and even on 

 the Scanic peninsula confined to one described species, here 



