THE BUTTERFLY. 



59 



single joint, which becomes enormously devel- 

 oped in the butterfly to form a sucking organ of 

 curious construction ; while the outer appendage 

 becomes the maxillary palpus, reduced to a couple 

 of minute joints or even less, only to be detected 

 by the most careful observer, and physiologically 

 null. As this sucking mouth is one of the most 

 characteristic parts of the perfect butterfly, we 

 will examine it more closely. Although almost 



ant. 



FIG. 68. Cross-section of the maxillae or tongue of Danais Plexippus (the 

 anterior portion uppermost) to show the mode in which the two halves unite 

 to form a central canal (c); fr% tracheae; n, nerves ; m, ra 2 , muscles of one side; 

 X about 125 (Burgess). 



entirely concealed when coiled, it is frequently as 

 long as the entire body, and consists of two lat- 

 eral halves united down the middle ; each part is 

 composed of an immense number of short, trans- 

 verse rings, which are convex on the outer sur- 

 face, concave on the inner [Fig. 68] ; and it is by 

 the union of these inner concavities that a central 

 tube is formed. The lateral rings are also partial- 

 ly hollow, and have, therefore, been supposed by 



