THE IldUSE FLY 



4:l 



The labella? consist of a 

 mass of tissue through 

 which run spirall\'-coiled 

 rods radiating from a horse- 

 shoe-shaped rim. The la- 

 bella? are probably homol- 

 ogous to tlie labial palpi, 

 and tile palpi are maxillary 

 pilpi. 



LABEI^L.-K OF HOUSE FLY'S PltOBOSCIS. 



The liorseshoe-shapecl rim seems to constitute tlie 

 end of the sheath, and through its opening the kmcets 

 work. Tlie sheath is homologous to the labium. 



The lancets are enclosed in 

 the sheath, and are homol- 

 ogous to the maxilUv. They 

 are moved up and down l)y 

 two chitinous rods to which 

 muscles are attached. 



LANCETS AND PALPI oK HOUSE FLY. 



(LabelUe removed.) 



Tlie lancets pierce the skin of an animal, and the 

 labellee and sheath constitute a sucking organ by 

 which the blood is drawn from the puncture. 



