368 THE ANATOMY OF LNTERTEBRATED ANIMALS. 



mals, birds, and bees, a circular wall, or short proboscis, in- 

 vests the other parts of the mouth. There are, first, two 

 lateral, protrusible, horny plates ; secondly, an anterior and a 

 posterior seta ; the latter stronger, and grooved longitudinally 

 in front. Between these is a single fine seta. Gerstfeldt 

 considers that the last answers to the hypopharynx ; the 

 second pair, to the labrum and the second maxillae ; the first 

 pair, to the first maxillae ; and that there are no mandibles. 



Fig. 108.— Syrphus ribesii.—A. Larva. B. Papa. C. Imago. (" Regne Animal.'') 



The ordinary Diptera, which possess one pair of functional 

 wings attached to the mesothorax, resemble the Hemiptera 



'Svo 



Fig. 109.— EHstalis jloreus.—d, front of the head: e, labram; /. mandible : g. maxilla 

 and palpus ; i, labium ; r'. extremity of the labium separately and more magni- 

 fied; **i, inner surface of the para<*!o«s9e ; ***i. the rows of hairs on the inner 

 surface ; I, the ligula ; m, the cardo and submentum. (After Newport.) 



in possessing a usually fleshy proboscis, often tumid at its 

 extremity, which is formed by the confluent second maxillae. 



