38 Annals Entomological Society of America [Vol. VIII, 
The above characteristics concerning the maxillary sclerites 
(mx. s.) and the paired piercing organs (mx.) may be found in 
all thrips as far as observed and one can safely infer that the 
similar parts in all thrips are homologous and should have the 
same interpretation thruout the order. In a lke manner it 
will be found that a similar homology exists between the 
asymmetrical piercing organs of all thrips. This homology 
eliminates the suggestion offered by Muir and Kershaw that 
in the two suborders of the Thysanoptera a distinct difference 
of interpretation of the piercing organs might be possible. 
Heliothrips femoralis (fig. 1, 2, 5, 12, 18, 19, 27, and 28).— 
The maxillae of Heliothrips are in general typical of the sub- 
order Terebrantia and accord with the general description 
of the maxillae just given. The maxillary sclerites (mx. s.) 
of the nymph and adult resemble each other except that the 
palpi of the nymph are four-segmented while those of the 
adult consist of only two long segments. The palpi of some of 
the more generalized adult Aeolothripidae are four-segmented 
and thus the four-segmented palpi of the nymph indicate a 
generalized condition. The maxillary sclerites (mx. s.) are 
decidedly asymmetrical. This asymmetry is more pronounced 
in the adult (fig. 1). The proximal ends of the maxillary sclerites 
of the adult are not in direct contact with the head-capsule. 
There are distinct membranous areas (me.) between them. 
In this particular species the membranous areas (me.) continue 
from .the cephalic margin of the maxillary sclerites to the bases 
of the palpi where the membranes broaden and surround the 
proximal segments. The membranous strip on the left maxil- 
lary sclerite is more extensive than the one on the right. The 
ento-mesal extensions (et.) arising from the lateral margins 
of the maxillary sclerites resemble closely the general descrip- 
tion of these parts and they can be readily made out in figures 
28 and 39 to 44. 
The paired piercing organs of Heliothrips (fig. 27 and 28, 
mx.) are but slightly longer than the maxillary sclerites and 
this is true of the Terebrantia in general. The structure of 
their paired piercing organs resembles the general description 
of these parts. The proximal piece in the nymph is L-shaped 
and the base of the L articulates along the dorsal margin of the 
maxillary sclerite (mx. s.). The proximal piece in the adult, 
