40 THE CHRYSALIS. 



the proportionate extent of this part is still the 

 same ; showing that the sheath is expanded at 

 this point simply to fill up the angular void left 

 on obliquely uniting legs from opposite sides of 

 the body, and that the surface we see is a com- 

 mon lid under which are thrust the tongue and 

 the palpi. There is another curious thing about 

 this part ; very f reqiiently the base of the tongue 

 is not covered by this lid at all, 

 but by a separate piece of its own 

 [Fig. 52], which, unlike the lid be- 

 yond, is not divided down the mid- 

 dle to represent the two halves of 



vieAv ' of' "theTront the tongue. This appears to be a con- 

 portion of the 



of EU- stant phenomenon in some butter- 



Philooice, 



1 covering flies 5 but in others (compare Figs. 50 

 f n as e ai an( l 51) it is sometimes present and 

 tongue "hffeath'; \\ at others absent ; that the tongue 



fii>t pair oflegs ; 2, . , . n . n . . . 



second pair of legs; itseli is not exposed at this point is 



a, antenual sheath. 



proved by its being formed of a 

 single, not, as the tongue itself, of a double piece. 



Next the extreme base of the tongue, and abut- 

 ting against it on either side, are the mandible- 

 cases, small plates, not separated at their base 

 from the integument of the head, and often re- 

 duced to mere tubercles ; indeed their appearance 

 is so slight that I do not know if their existence 

 has ever been specially noticed. 



On either side of the head, close to the base of 



