THE ORAL ORGANS OF THE GAD-FLY. 127 
regularly set, saw-like teeth, decreasing slightly in size from the tip 
towards the base. It is almost impossible to represent these teeth 
exactly in a drawing, so small are they. According to Gosse, 
twelve of them are cut in a length of one ten-thousandth part of 
an inch, 
Referring to Fig. 37 again, on each side of the mandibles are 
found the maxzl/@ (mx.) In structure, these are rather more com- 
plex than the former. Of about the same length, they are much 
narrower, and in place of being flattened, they are thickened into a 
bayonet-like form, triangular in section, of which the base is 
widened out. Like a bayonet, too, they bend a little backwards 
near the point, and present a blunter termination than is found in 
the mandibles. The maxille are also armed with a formidable 
array of teeth, the arrangement of which is peculiar and rather 
difficult to describe. Reference to Fig. 38 will here perhaps be 
of some assistance. 
Of the three sides of the maxilla, one is broader than the other 
two. Commencing at the dilated basal part, this side is found to 
be deeply channeled, or grooved, quite up to its edges. ‘The groove 
gradually narrows and becomes less deep in the direction of the tip, 
leaving thus, on each side, a marginal surface gradually broadening 
until the groove disappears near the tip. Here there are closely 
set a number of strong, recurved teeth carried to the extreme point 
