22 [June, 



ON MUSCA HORTORUM, FALLEN, AND ALLIED SPECIES. 

 BY E. H. MEADE. 



It has been well said, that an Entomologist who aspires to be 

 anything more than a collector or dabbler in science, must confine 

 himself to the study of one Order of insects ; and if he has but 

 little time at his disposal, devote most of his attention to one family 

 in that Order : he can only thus acquire an intimate and critical ac- 

 quaintance with the characters of the species which it contains, or of 

 their life history. 



In many genera there are small groups in which the species bear 

 such a close general resemblance to each other, that several species have 

 been confounded together by the older authors. This has principally 

 arisen from their neglecting to observe and record minute points of 

 structure, such as the number and disposition of the hairs and spines 

 on the legs, wings, or body of the insect ; which are often exceedingly 

 valuable specific characters, being mostly constant, and not liable to 

 vary like size and colour. 



The descriptions of the older Entomologists were also generally 

 so brief, that they often apply equally well to two or three distinct 

 species, and there is very little doubt that they frequently were so 

 applied ; the author confusing two or three species. Much learning 

 has sometimes been brought to bear on this subject, in the endeavour 

 to ascertain the precise species to which a name has been applied ; 

 but if this point can be cleared up at. all, it must be by the examination 

 of typical specimens preserved in Museums.* 



It is to one small group in the restricted family of Muscida that 

 I wish to direct attention. In our gardens and groves, and on the 

 road-side hedges, a very common fly may be found of a blue-black 

 colour, marked with white reflections, rather larger than the ordinary 

 house fly (Jfusca domestical), which has been long known as the garden 

 fly (Musca horiorum). Upon careful examination it will be found 

 that two distinct species (both common in most places in England), 

 have been confounded by all the older Dipterologists, and are still but 

 imperfectly known, different authors who have distinguished them 

 having described them by different names, in ignorance of the writings 

 of others ; so that the synonymy is in great confusion. 



Eobineau-Desvoidy, in his great work upon the Myodaires, pub- 

 lished in 1830, first pointed out that there were several distinct species 



* Meigen's collection of Diptera is in the Jardin des Pluntcs, in Paris; Macquart'a in the . 



Museum of bis native city, Lille ; Fallen's is in Stockholm. 



