52 Annals Entomological Society of America [Vol. VIII, 
Considerable variation occurs in regard to the exact location of 
these glands and the position and points of union of their ducts. 
One of the two pairs of salivary glands (fig. 15 and 24, 31) 
in the thorax and abdomen of the two species here considered 
is long, tubular and more or less homogenous thruout its length 
1. s.g.). This pair is located laterad or dorsad of the alimentary 
canal and continues caudad into the abdomen. Longitudinal 
sections thru these glands show that they are homogenous, 
nucleated and apparently syncitial. 
The second pair of salivary glands (fig. 16 and 30) are short, 
thick and more or less irregular in outline and usually confined 
to the thorax (s. s. g.). The cells of these glands are large and 
the cell walls are distinct. The nuclei are prominent and 
stain deeply. The protoplasm of the tissue stains un- 
evenly and is more or less filled with vacuoles. A distinct 
centrally located lumen extends thruout the entire length of the 
gland. 
The above two pairs of salivary glands give rise to ducts 
(1. d..and s. d.) at their cephalic ends. The four ducts extend 
into the head laterad and dorsad of the oesophagus. In the 
region between the supraoesophageal and suboesophageal 
ganglia the ducts turn ventrad and continue to the y-shaped 
chitinous structure (y.) caudad of the pharynx (fig. 28, 45, 49, 
58 and 59.). Within this structure or before entering it the 
four ducts unite into a common duct and this common duct 
(c. d.) continues ventrad to the apex of the mouth-cone. The 
secretions from the salivary glands are thus poured into the 
punctures in the host plant which are made by the mouth-parts. 
When thrips puncture green leaves or colored flowers the area 
about the puncture becomes light in color. This discoloration 
is undoubtedly due to the action of the salivary secretion on 
the plant tissue. 
The y-shaped piece (y.) caudad of the pharynx in all thrips 
is a characteristic structure. In both suborders this piece is 
somewhat different in shape (fig. 35 and 47) but it has the same 
relation to the mouth-parts. There is a distinct muscle band 
or there may be several bands (mu.) extending between the 
base of the arms of the y and the dorsal part of the caudal aspect 
of the pharynx (ph.). Possibly, on contraction, these muscles 
move the y-shaped piece in such a manner as to control the flow 
from the salivary glands. The exact homology of the y-shaped 
