THE ESOPHAGEAL VALVE OF SOME 
AQUATIC HEMIPTERA 
By Margaret C. Parsons 
Harvard Biological Laboratories, Cambridge, Mass. 
Only two previous comparative studies have been made 
on the esophageal valves of the aquatic Hemiptera. Sutton 
(1951) described this region in Sigara falleni Fieb. and 
Corixa punctata Ullig, and compared it briefly with the 
valves of naucorids and notonectids. More recently, Marks 
(1958) compared the esophageal valves of four species of 
aquatic Hemiptera, representing four different families; 
Notonecta undulata Say (Notonectidae) , Ranatra fusca 
P.B. (Nepidae), Belostoma flumineum Say (Belostomati- 
dae), and Hesperocorixa escheri (Heer) (Corixidae). 
In the present investigation, the valves of the first three 
species of Marks were studied. The Corixidae used were 
Sigara ornata (Abbt.) and Hesperocorixa interrupta 
(Say) ; Pelocoris femoratus P.B., representing the family 
Naucoridae, was also examined. Both transverse and longi- 
tudinal serial sections through the valve were employed, 
the digestive tracts being fixed in aqueous Bouin’s, alcoholic 
Bouin’s, Held’s, and Zenker’s fluids and sectioned by the 
paraffin method. The stains most commonly used were 
Mallory’s triple connective tissue stain, Mallory’s phospho- 
tungstic acid hematoxylin, and Delafield’s hematoxylin and 
eosin. 
The purposes of the present paper are (1) to compare 
the esophageal valve of Pelocoris with that of the other 
aquatic Cryptocerata, and (2) to offer a few comments on 
the works of Sutton (1951) and Marks (1958). 
I wish to thank Mr. Edwin P. Marks and my husband, 
Dr. Thomas S. Parsons, for their valuable suggestions in 
connection with this problem. The research was carried out 
partly during the tenure of a National Science Foundation 
Predoctoral Fellowship and partly under the Ellen C. Sabin 
Fellowship, awarded by the American Association of Uni- 
versity Women. 
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