8i 



and examine the beak before dissection. The long, three- 

 jointed labium^ forming all of the beak as seen superficially, 

 is specially chitinized (brown) near its distal end. The dis- 

 tal joint is the longest, and its surface is sparsely covered 

 with fine, whitish hairs. The tip is rather blunt than acute. 

 A narrow channel, widest at its proximal end, runs along the 

 upper face of the labium. In this channel, but concealed 

 by the approaching edges of it, lie the mandibles and max- 

 illae. A glimpse of the mandibles and maxillae just at the 

 base of the labium can often be had. Above the base of the 

 labium is the minute, acute-angled labium lying just over 

 the entering mandibles and maxillae. 



With a dissecting needle carefully break away the head- 

 wall and muscle near the base of the beak, especially dorsad 

 and laterad. The bases of the ittandibles and viaxillcB will be 

 discovered as small, strongly chitinized (brown), terminal 

 dilations of slender, chitin rods, which run forward into the 

 channel of the labium. Note the relative position of the 

 two rods with dilated bases on either side, and decide which 

 is mandible and which maxilla. (The rod lying slightly 

 dorsad and laterad of the other is the mandible ; the man- 

 dible is also thicker and larger than the maxilla.) Trace the 

 slender chitin rods or stylets (the mandibles and maxillae) 

 into the channel of the labium. Here they are all closely 

 appressed, the two maxillae specially so, so that they can be 

 separated only with difficulty. 



Remove the mandibular and maxillar stylets and note the 

 channel in which they naturally lie. The labium is more 

 strongly chitinized along the walls of the channel than else- 

 where, except at its tip. 



Make a drawing of the mouth-parts from dorsal view, 

 with the mandibles and maxillae removed from the channel 

 of the labium and spread apart. 



