106 
PEDAL GLANDS. 
water within a system of vessels wliieh may or may not communicate 
with the circulatory hlood system ; the orihces supposed to he aquiferous 
are, however, merely the outlets of aggregatetl mucous glands or the 
vestigial opening of the hyssogenous gland which are all placed on the 
posterior side of the foot. In Xaticd josephimi, a marine Gastropod, 
it has, however, been fully establi.shed that, ([uite independently of the 
l ilood system, the foot does contain a very comple.x and extensive water 
vascular system, hy means of which the foot can he very rapidly 
expanded and extended for locomotion. 
'fhe surface of the foot is richly ciliated and furnished with a great 
number of unicellular mucous glands, but there are also distinct 
invaginations of the ectoderm or integument, known as Pedal glands, 
where mucous cells are aggregated together and distinctly localized. 
An Anterior Pedal Gland is i)ossossed by the active a(|mdic Strep- 
tonenres, which opens at the anterior end of the foot by a transverse 
groove and secretes mucus for 
the lulirication of the foot and 
to aid in the process of crawling. 
This gland is represented in the 
Puhnonates and in terrestrial 
Streptoneures by the Snpra- 
I’edal gland, known also as the 
sinus of Kleehurg, a long e])ithelial tube with ciliated ventral snrfiice, 
jilaced between the muzzle and the foot, which was formerly thought 
to he an oltactory organ, Imt 
which serves as a reservoir and 
duct for the mucus which its 
inve.sting cells abundantly 
secrete. In C^clostfinid this 
gland becomes bihd posteriorly 
in harmony with the longitu- 
dinally divided foot. 
'I’he Ventral Pedal tSinus is 
found in Cydmfnmd and many 
Streptoneures, being comparable 
with the byssal cavity of the 
Pelecypods. It opens on the 
anterior portion of the foot-sole, 
torming the apertiu'e of the sole gland, whose glandular epithelial 
Fua 387. — Prosoma of Helix x 2, r'howing ihe 
position of the Supra-Peclal Gland, 
Fig. 388. — Supra-Pedal Gland of Cyclosto7)ia 
elegans{ 2 i{\.^x Siniroth), highly magnified, showing 
the bifid posterior prolongations. 
