1915] The Head and Mouth-Parts of Thysanoptera 53 
structure is not clear but its general position and structure, 
its opening into the mouth-cavity and its relation to the sali- 
vary ducts would indicate that it is homologous with the salivary 
syringe of the Hemiptera. 
Heliothrips femoralis—The long, narrow, tube-like glands 
(fig. 31 and 24) are located laterad of the alimentary canal 
(1. s. g.) and extend from the metathorax caudad to about the 
fourth abdominal segment. Figure 24 shows that the gland is 
narrow and has a straight lumen extending thruout its length. 
The ducts from these glands (fig. 31, 1. d.) are enlarged and 
located dorsad of the oesophagus in the region of the pro- 
thorax and mesothorax. The enlarged portions of the ducts 
serve as reservoirs for the secretion. The ducts from these 
similar right and left glands unite with each other before 
entering the y-shaped structure caudad of the pharynx. 
The short, thick, oval glands (fig. 30, s. s. g.) in the thorax 
are about the length of two segments and located laterad of the 
oesophagus. The right gland is usually confined to the meta- 
thorax and the first abdominal segment. The cells of these 
glands are exceedingly large and distinctly differentiated. 
One or two deeply staining, irregular nuclei can be seen in each 
cell, and the protoplasm of the cells stains more or less unevenly. 
The ducts from these glands (s. d.) have about the same thick- 
ness thruout. In the region of the head they are somewhat 
larger than the ducts from the above glands in the same region. 
The duct from the left gland unites with the duct from the 
right similar gland before entering the y-shaped piece (fig. 40, 
45 and 58). Within the y-shaped piece the united ducts from 
the two kinds of glands join and form a common duct which 
continues to nearly the apex of the mouth-cone. 
Cephalothrips yucce.—The long, tube-like glands of Cephalo- 
thrips (fig. 15, 1. s. g.) are located laterad of the alimentary 
canal and extend from the prothorax into the first or second 
abdominal segment. These glands are homologous with the 
long, tube-like glands in Heliothrips, but they are thicker 
and have a sinuous lumen thruout their length. The cell 
consistency is about the same as in Heliothrips. The ducts 
extending from these glands into the head are very small and 
not dilated in the thorax. 
