EXPLANATION OF PLATE XV 
Fig. 12.—Section through everted labella in the plane of the fork (e) 
where the dorsal and ventral folds of the epidermis (d r) 
are well marked. In the next proximal section the tips of 
the fork are seen to extend into the angle of the third 
fold (r 6 ), here indicated by dotted lines. Note that the 
tooth plate has entirely disappeared and the labial gutter 
0 '< r *) is now well formed, though the upper sclerites are 
still free. The approximate plane of this section is between 
c 6 and e in fig. 14. x 570. 
* 3 - Pocket formed by the infolding of the epidermis in the 
plane near d 2 in fig. 14. Here the upper sclerites (r) of 
the labial gutter have become fused with the lower (r 1 ). 
x 570. 
^ '£• ! 4 - -Dorsal aspect of everted labella and distal portion of labium, 
from a well cleared preparation. Compare this with fig 2, 
which was drawn from a preparation which had not been 
sufficiently cleared. 
P'g- 15 Distal portion of labrum. x 200. 
Fig. 16. -Extreme tip ol same showing the scaly dorsal structure, 
x 570. 
^ Section through tip of labrum. x 570. 
1 ig- 18. Section of labrum through the plane just in front of the 
ventral thickening (fig. 15, a 1 ) carrying minute hairs, 
x 750. 
19 Section of labrum through ventral thickening (fig ! 5 > 
showing minute hairs. x 750. 
