48 Annals Entomological Society of America [Vol. VIII, 
corner of the maxillary sclerite and the base of the left man- 
dible. The right mandible in the reduction of the mouth-cone 
has given rise to a distinct, crook-like, ental projection. The 
above modifications are typical for the suborder Tubulifera as 
far as observed. 
Muir and Kershaw interpreted the left, asymmetrical 
piercing organ as a part of the maxille in their work on one 
species of Tubulifera. ‘‘The unpaired setz arises from the left 
maxille and is a part thereof.’ It is readily understood how 
such an error came about, since only the adult stage of a single 
species of Tubulifera was studied. The connection of the left 
asymmetrical piercing organ in the adult with the left maxil- 
lary sclerite is secondary. This connection does not show in 
the nymph. 
PHARYNX. 
If one examines the mouth-cone of various species of thrips, a 
short, heavily chitinized, ham-shaped piece is always found just 
beneath the clypeus. Stained and sectioned material shows 
clearly that this piece is a structural modification of the ali- 
mentary canal, fitted for sucking and homologous with the 
pharynx of sucking insects (fig. 5, 6, 19, 27, 35, 38-46, 48, 49 
and 52-59). Jordan figures this particular piece and calls it 
the hypopharynx of the pharynx, while his epipharynx is what 
we have interpreted to be the left mandible. 
Structurally the pharynx consists of one piece except for a 
small, chitinized, transverse area (t. a.) at the caudo-dorsal end 
(fig. 46 and 48). However, in respect to size and shape the 
pharynx is divided into two regions. The ventral half is a 
small, chitinized tube which opens within the ental groove 
of the labrum, while the dorsal half widens out into a broad, 
thick region. The entire pharynx resembles a gourd dipper 
which has had removed from one side almost one-half of its 
enlarged portion, and across this cavity there has been placed 
a concave, elastic membrane (e.) to which muscles (d. m.) 
are attached. On the caudal side of the enlarged portion there 
are two small openings. Glandular ducts (d.) pass thru these 
openings and pour their secretions into the sucking chamber. 
When the pharynx is sectioned in one of three planes, 
frontal, sagittal and transverse, it shows a centrally located 
canal extending thru its entire length. This lumen starts with 
