254 



Flash lk; UTS o\ Xatcrk 



LA. 



MP. 



true flies still retain, in ino-^t ca^es, tin- two tiii\ 

 poiseis (»r balanceis, jii^t to leiuiiul ll^ ot then 

 descent trDUi lOnr-win^ed ancestors. Natme has 

 no habit more interesting than this retention ol 

 parts lonj4 since disused or almost disused ; by 

 their aid we are able to trace the j^enealo.^y ol 



plants and am- 

 mals. 



in \o. I I we 

 have a dissec- 

 ted view of the 

 mouth-orj^ans 

 and blood-suck- 

 ing apparatus 

 of the i^adfly, 

 inunensely en- 

 larged, so as to 

 show in detail 

 the minute struc- 

 ture. In life, 

 all these separate 

 parts are com- 

 bined together 

 into acompound 

 sucker (com- 

 monly called the proboscis), which forms practi 

 cally a sin;4le tube or sheath ; thev are dissected 

 out here for facility of comprehension. The lonj^est 

 part, marked L.\ in the sketch, is the labium or 

 lower lip, which makes up the mass of the tube ; 

 it ends in two soft tinker-like pads, which are fleshy 

 in te.\ture, and which enable it to lix itself firmly 



NO. II. — THE C.ADKI.Y S lANCKIS. \vn n 

 OTHER I'AklS (IK TMK rROUosCls. 



