APHANIPTERA. 421 



Subdivision 3 (DicJiceta). Sucker with two lancets. 

 This subdivision comprises an immense assemblage 

 of species, constituting the Linnsean genera (Estrus, 

 Conops, and Musca, after the removal of the Syr- 

 phid(B but, owing to the numerous divisions and 

 subdivisions necessary for its investigation having 

 but little to interest the general reader, I shall not 

 here detail them. 



SECTION II. (Pupipara ; HOMALOPTERA, Leach). Head 

 immersed in the front of the thorax ; sucker inclosed 

 in two valves ; claws with many teeth. The transform- 

 ations to the pupa state undergone in the body 

 of the parent fly. 



Fam. 1 (Hipposcidce). Head frontal. 

 Fam. 2 (Nycteribiidee}. Head dorsal. 



ORDER xii. APHANIPTERA (Kirby ; Siphonaptera, 



Latreille; Suctoria, De Geer; Aptera, MacLeay). 

 This order consists of the various species of fleas which in- 

 habit the bodies of man and various animals and birds, in 

 which the body is of small size, clothed with a hard shining 

 integument, armed with sharp bristles arranged in transverse 

 series upon the back 

 and legs. It is very 

 much compressed and 

 apterous ; at least rudi- 

 ments only of wings and 

 wing-cases exist in the 

 shape of two flattened 

 plates, on each side of 

 the body, near the base 



The flea (Puletirritan,). of the posterior legS. 



The mouth consists of 

 the six ordinary parts, but is of an elongated suctorial form, 



