1915] The Head and Mouth-Parts of Thysanoptera 39 
likewise articulates against the cephalic margin of the maxillary 
sclerite and has an L-shape, but the base of the L is greatly 
reduced and the erect portion is longer, heavier and of the 
same thickness thruout. The above relation between the 
paired piercing organs and the maxillary sclerites is true of all 
Terebrantia as far as observed (fig. 14, 21 and 32). Since 
the paired piercing organs in the Terebrantia are directly 
connected with the cephalic margin or the latero-cephalic 
corners of the maxillary sclerite, one may conclude, as Garman 
has already done in his work on Limothrips cerealium, that these 
piercing organs are parts of the maxillae. If such is the case 
the paired piercing organs may be modified lacinia as Garman 
has suggested. According to Garman and other workers 
these organs consist of only two pieces, but in all species observed 
three distinct pieces can be found. The suture between the 
needle-like distal portion and the middle piece is wanting in 
the figures of other workers. 
Karl Jordan and other workers have interpreted the paired 
piercing organs (mx.) as mandibles. Jordan worked with 
Heliothrips haemorrhoidalis, a form closely related to Helio- 
thrips femoralis. His proof is largely founded on the state- 
ment that the embryonic development shows that these pieces 
are mandibles. The evidence in support of this statement 
is wanting in both figures and discussion. He has but one 
figure of the embryonic condition and in this the relation of the 
so-called mandibles to the head-capsule and other parts is 
not clear. The real difficulty with Jordan’s interpretation 
rests in the fact that he has wrongly identified the asym- 
metrical piercing organ (l. md.) and consequently in his 
search for mandibles he has from necessity tried to show that 
the paired piercing organs are mandibles. 
The conclusion in regard to the paired piercing organs of 
the Terebrantia is that they are portions of the maxillae, and 
the following additional evidence will be presented to sub- 
stantiate the same. 
In the first place, if these paired piercing organs are mandi- 
bles, how can one explain their three piece structure? Mandibles 
usually have only one solid piece, but maxillae on the other hand 
are composed of several sclerites and upon modification they 
might assume the conditions found in thrips. As to the exact 
