136 
Psyche 
[December 
The Esophageal Valve of Pelogoris fematorus P.B. 
Figure A and Text-figure 2 show the general structure 
of the Pelocoris esophageal valve. The invagination consists 
of two layers of foregut epithelium, an inner and an outer 
one, which are continous with each other. The cells of the 
outer layer are somewhat taller than those of the inner 
one. In most of the specimens examined, the two layers 
are contiguous, but a few individuals show a small intra- 
valvular space between them. Such intravalvular spaces 
contain fine connective tissue fibrils, but never muscle. 
The cells of the outer cell layer become taller at the an- 
terior limit of the invagination, where they gradually merge 
with the annular cells, a ring of tall cells encircling the 
foregut-midgut junction. This corresponds to the “terminal 
pad” of cells described by Marks in other water bugs, and 
will be discussed later. The annular cells, like those of the 
invagination, have basally located nuclei, and are covered 
by a cuticular intima which is continuous with that of the 
esophagus. The intima adheres closely to the annular cells, 
but is pulled away from the epithelium of the invagination 
to form a definite “entonnoir” (Aubertot, 1934), similar 
to, although not as pronounced as, that of the Corixidae. 
The entonnoir and the cells of the invagination are usually 
connected by fine strands of cuticula which run from the 
entonnoir to the spaces between the cells. 
The cells at the posterior tip of the invagination usually 
contain, at their apical ends, large vacuoles. Such vacuoles 
occur less frequently in the more anteriorly located cells 
of the inner and outer cell layers or in the annular cells. 
Their presence appears to be connected with the secretion 
of the intima, since in many cases they seem to be passing 
from the cells into the space between the epithelium and the 
entonnoir. 
Explanation of Plate 12 
Figure A. Photomicrograph of the esophageal invagination of Pelocor- 
is femoratus. See Text - figure 2 for explantion. Held’s, Delafield’s hema- 
toxylin and Eosin Y. 225 X. Figure B. Photomicrograph of the annular 
cell region of Sigara ornata. See Text - figure 3 for orientation. Aqueous 
Bouin’s, Delafield’s hematoxylin and Eosin Y. 600 X. 
