1958] Parsons — Gelastocoris 103 
tima and the small nuclei remain. Such regions are not 
confined to any definite area of the gland, and their loca- 
tion varies from one individual to the next. The epithelium 
is never more than 15 or 20 \i thick, and the bulk of the 
gland consists merely of the very extensive lumen filled 
with a homogeneous, finely granular secretion which stains 
blue in Mallory’s triple connective-tissue stain and pink 
in Delafield’s hematoxylin and eosin. 
These glands in the Gelastocoridae resemble in several 
ways the cephalic glands of aquatic Cryptocerata, and the 
similarities suggest that the former are homologous with 
the latter. Their paired ventral position in the head cor- 
responds to that described by other authors for the cephalic 
glands of the Notonectidae, Naucoridae, Belostomatidae, 
and Corixidae (in the last family only the anterior part 
of the gland is ventral, the posterior part being dorsal to 
the brain) . The simple ss^Mke shape ot the gelastocorid 
glands is consistent wi® the previous descriptions of ceph- 
alic glands in aquatic bugs; to the authors knowledge, only 
the Naucoridae show a more complicated structure, having 
a lobed reservoir beside the glandular part of each gland 
(Becker, 1929; Rawat, 1939). A muscle controlling the 
opening mechanism of the gland has been described in 
Corixa and Notonecta (Benwitz, 1956) and in Naucoris 
(Becker, 1929) ; although in the former two genera this 
muscle originates on the wall of the head, in Naucoris it 
is attached, like that of Gelastocoris, to the tip of the poster- 
ior wing of the hypopharynx. ^ 
Histologically there are further resemblances. The three 
main components, the large cells, the smaller cells, and 
the chitinous intima, are mentioned in Corixa (Benwitz, 
1956), Naucoris (Rawat, 1939), Ranatra (Bugnion and 
Popoff, 1908), and Notonecta (Bordas, 1905 a). The secre- 
tory epithelium is reported to be arranged into acini in 
Naucoris (Becker, 1929; Rawat, 1939) and Notonecta 
(Bugnion and Popoff, 1908), but no such arrangement is 
mentioned for the other forms. Locy (1884), Bugnion and 
Popoff (1908), and Benwitz (1956) report intracellular 
canaliculi within the large cells, similar to those seen in 
