14 AN A ceo VNT OF BRITISH FLIES. 



by a seta. Proboscis generally withdrawn into a 



cavity, with two setae. Pupa coarctate = {Syr- 



phidie, ConopidcB, Muscidci). 

 Section 2. — (Stirps 5.) Pupipara = Homaloptera (Leach). 



Head immersed in the thorax. Claws denticulated. 



Larvae nourished in the mother = [Hippoboscidea, 



etc.). 

 Since Westwood's classification (1840) several alterations have been 

 made. In 185 1 Walker's " Diptera, Insecta Britannica," in three 

 volumes, was published. This is the fullest account of British flies 

 that has been published. A great number of species are described in 

 it, many of which seem to be of doubtful repute. In this work, which 

 is, unfortunately, out of print, the following classification is adopted. 

 The Diptera are divided into three groups: i. Suctoridea ; 2. Pro- 

 boscidea ; 3. Fproboscidea, according to the following characters : 



nj c Lying flat in cavities at the sides of the head - i 



5 c < Seated in front of ^ ^ f close, side by side - 2 



■^ ' the head. ° I distant - - - 3 



The second group, or the Proboscidea, is divided into three 

 sections : i. Neinocera ; 2. Brachycera ; and 3. Hypocera {Phoridce). 



It will be seen that this third section is done away with in Verrall's 

 list, and that the family Phoridtn is placed in the Proboscidea, just 

 in front of the Eproboscidea. 



The Ap/ia?iipfera, or fleas, are included in the Diptera by Walker, 

 who enumerates fourteen species ; while Verrall, in his recent list, 

 only mentions thirteen species in this family. It will be seen that a 

 large number of species mentioned by Walker are cut out by Verrall, 

 as he considers their record doubtful. 



In Kirby's "Text-book of Entomology " (18S5) the Aphaniptera 

 are also included in the order Diptera. In this book is also men- 

 tioned Westwood's order, the Achreiopkra, as being possibly included 

 here. They are not, however, British insects, being parasitic on the 

 beaver and somewhat resembling a small cockroach. 



This author divides the Diptera into four sub-orders, namely : 



1. Diptera Aphaniptera. 



2. ,, Nemocera. 



3. ,, Brachycera. 



4. ., Homaloptera. 



The most recent classification is that adopted by Verrall, published 

 in 1888 ;* and it is this classification we intend to use. 



* "A List of British Diptera." By H. Verrall, F.E.S., 1S8S (Pratt & Co.). 

 This classification was introduced by Brauer. 



