THE FOOD PUMP OF PELOCORIS 
AND COMPARATIVE STUDIES ON 
OTHER AQUATIC HEMIPTERA 
By Edwin P. Marks 
Washburn University, Topeka, Kansas 
Introduction 
In earlier studies it has been found that in the Corixidae 
(Griffith 1945, Sutton 1951, Benwitz 1956, Marks 1958) 
and in the Notonectidae (Marks 1958) the buccopharyn- 
geal pumps contain rather complicated armatures apparent- 
ly derived from the remnants of the hypopharyngeal 
suspensorium. When the opportunity was provided to 
study this closely related form, therefore, it was quick- 
ly accepted. Twelve specimens of Pelocoris femora- 
tus P.B. from ponds in the Cambridge, Mass, area were 
obtained. Several were killed in chloroform and dissected 
immediately. Three were cleared in caustic, lightly stained 
in acid fuchsin, and placed in glycerin. The last makes an 
excellent medium for dissection of both cleared and un- 
cleared specimens because of both its property of rendering 
the material transparent, and its viscosity, which holds the 
specimen in place for drawing or photographing. The 
dissections were photographed by Dr. Thomas S. Parsons 
and then drawn by the author for the purpose of illustra- 
tion. 
Thanks are due to Dr. and Mrs. Parsons for their 
hospitality and their help with many technical details, and 
to Prof. Frank M. Carpenter and the Department of Bi- 
ology of Harvard University for the facilities which made 
this study possible. 
Description 
When the ventral wall of the head is removed, the 
muscles of the stylets are exposed. These muscles and the 
attached stylets can be removed by gently withdrawing 
them from their attachments and sliding them out of the 
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