PREFACE. 



THE second volume of DIPTERA of "Insecta Britannica" com- 

 prises the latter part of the Brackycera, with the Hypocera and 

 the Eproboscidea. In the BracJiycera two families are described, 

 the Muscida and the (Estrida, and the former is divided into 

 sixteen subfamilies. Upon closely examining the little-studied 

 families contained in this volume, the number of species has been 

 found very much greater than was anticipated, and, as we are 

 limited to a certain number of pages, only a portion of the 

 species could be given. The British Diptera seem to be as 

 numerous as those of Scandinavia, which Zetterstedt, in his ela- 

 borate work, occupied eleven volumes in describing. The sub- 

 families above mentioned are here briefly noticed. The Myopides 

 and the Sarcophagides are mostly described. In the Tachinides about 

 half the British species of Tachina are omitted. The species of 

 this genus are very numerous, and require all their characters to 

 be fully detailed, in order to identify them with certainty, and the 

 omission of a precise notice of a single part of the structure is 

 sufficient to cause a doubt as to the species. The greater part of 

 the Muscides, and about half the Decides are described ; but the 

 Anthomyides in this volume probably do not exceed one-fourth of 

 the British species. Many species of Helomyzides, Lauxanides, 



