1976] 
Parsons — Morphology of Corixidae 
165 
All three corixids possess mesothoracic sensory membranes 
with radially arranged low folds (Figs. 25-27, M). In Hesperocorixa 
(Fig. 27) the membrane is oval and completely surrounded by sclero- 
tized areas; in the other two corixids it is round and anteriorly con- 
tinuous with the subalar membrane. The postalar bridge dorsal 
to it (Figs. 25-27, PP II), which forms only a weak lateral projection, 
is covered with flattened, scale-like structures in Micronecta (Fig. 
31) and Diaprepocoris (Fig. 32); similar scales were not observed in 
this region in Hesperocorixa. 
The sclerite of the scolopophorous organ is most elaborate in 
Hesperocorixa. The “Hagemann’s organ” of Corixinae has been 
described by many authors including Popham (1961), who believed 
it to be a pressure receptor, and Prager (1973), who found it to be 
sensitive to sound. Both these authors studied Corixa punctata, 
whose mesothoracic scolopophorous organ closely resembles that 
of Hesperocorixa interrupta. In both these Corixinae the sensory 
membrane bears a flask-shaped body (Fig. 27, FL) and a larger 
club-shaped structure (CL) whose base is considerably larger than 
its apex. The flask-shaped body (“B 1 ” of Popham 1961; “flaschen- 
formiger Korper” of Prager 1973) lies in the posterodorsal part of 
the sensory membrane and appears to contact the sclerotized rim 
of the scolopophorous organ. Immediately anteroventral to it lies 
the base (“B 2 ” of Popham; “Basis” of Prager) of the club-shaped 
structure. Popham, who studied the sense organ histologically, 
stated that the flask-shaped and club-shaped bodies are joined; the 
scanning electron microscope shows that they are at least in very 
close contact. 
The base of the club-shaped structure bears a pronounced knob 
(Figs. 27 and 33, SA) to which the scolophore attaches internally 
(Popham 1961). A narrow shaft joins the base to the dilated tip 
(“Kolben” of Prager 1973) of the club-shaped body, which extends, 
posteriorly and somewhat dorsally, beyond the rim of the sensory 
membrane and lies lateral to the metathorax. Popham (1961) 
believed that accidental flooding of the lateral subalar air space 
causes the club-shaped body to rotate until its tip touches the posta- 
lar projection (Fig. 27, PP II), thus warning the insect against 
tracheal flooding. Prager (1973) did not comment upon this hy- 
pothesis. 
