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[December 
appearance to those of the Corixidae that from the sections 
through the buccopharyngeal regions it would be almost 
impossible to tell which genus was being examined” (page 
489). The second type she characterized by “the presence 
of a small number of uniform teeth in the buccopharyngeal 
region”. From the figures (fig. 5, page 474, and fig. 6, page 
475) it is obvious that Pelocoris most closely resembles the 
second type. In all twelve specimens examined, the pumping 
apparatus was identical, there being apparently only one 
variety of this species in this area. In no case were speci- 
mens found which might be confused with corixids. 
In the three insects examined there is a second pulsatile 
area which lies posterior to the armature. This area reaches 
its greatest development in Notonecta where it is as well 
developed as the cibarial pump. In Pelocoris it attains a 
modest development, but is not nearly as prominent as in 
Notonecta. In Hesperocorixa, muscle Group 3 is reduced to 
a few strands at the entrance to the esophagus. In all cases 
these muscles are well behind the frontal ganglion and thus 
represent the posterior pharyngeal dilators. The action of 
this area is apparently to pass food on from the pharyngeal 
region into the esophagus. 
It is difficult to establish homologies between the parts 
of the sclerotized armatures of the three insects. At first 
appearance, when the preparations are studied from a 
ventral view (Plate 11, Figs, 5, 6, and 7), the homologies 
would appear to be as follows: 
a. The anterior lateral bars of Notonecta are unique 
and do not appear in the other groups. 
b. The posterior transverse bar of Notonecta appears 
homologous with the anterior transverse bar of Hesperoc- 
orixa. Both are activated by the posterior cibarial dilators. 
Both possess similar teeth. Both are posterior to the later- 
al constriction and the lateral fold. 
c. The sclerotized bar of Pelocoris appears to be homolo- 
gous to the posterior transverse bar of Hesperocorixa. Both 
are activated by the anterior pharyngeal dilators. Both 
occur at the point of greatest width of the pump. In both 
cases the apodeme is attached to an area behind the bar 
rather than to the bar itself. 
