1957] 
Marks — Food Pump of Hemiptera 
127 
of the cibarium, and they extend approximately one half of 
the length of the pump. The second group of muscles is 
both longer and heavier than the first. It arises on the pos- 
terior angle of the cranium and inserts on a large apodeme, 
which attaches in turn to the sclerotized bar in the dorsal 
wall of the pump. This group of muscles lies behind the 
frontal ganglion and thus miust represent the anterior 
dilators of the pharynx. These muscles will be referred to 
as “Group 2 They occupy approximately one-fourth of 
the length of the pump. The action of these muscles appears 
from micromanipulation to result in a rocking motion of 
the sclerotized bar so that the attached teeth sweep the 
floor of the pump. The third group of muscles is somewhat 
smaller than the others. These muscles, like the first group, 
insert on the midline of the roof of the pump by means of 
slender sclerotized apodemes. The muscles are somewhat 
longer and mjore slender than Group 1. They originate on 
the posterior angle of the vertex and make up the final one- 
fourth of the length of the pump. They serve to dilate 
the posterior pulsatile area, which carries food into the 
esophagus, and represent the posterior pharyngeal dilators. 
They will be referred to as “Group 3”. 
The membrane which makes up the roof of the pump 
varies in structure in the three portions of the pump. In 
the anterior portion, which is operated by the muscles of 
Group 1, the roof is a delicate memlbrane which is V-shaped 
in cross section. The dorsolateral edges are attached at 
the lateral margins of the pump and the dilator muscles 
are attached at the midline. This membrane is otherwise 
uncomplicated for the first one-third of its length. At this 
point an oblique fold appears in the lateral walls (Plate 
11, Fig. 4) and extends dorsally and posteriorly nearly to 
the lateral edges. The walls of this fold are more heavily 
sclerotized than the surrounding area and are yellow-brown 
in color. The folds formi a distinct landmark in the mem- 
brane. They possess no musculature, and will be called 
the lateral folds of the cibarium. 
Posterior to these folds, the membrane curves dorsally, 
forming a deep transverse fold (Plate 11, Fig. 4). This 
fold contains in its cavity a series of secondary folds which 
