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plete until the midgut is reached. This view is confirmed by the feeble 
rigidity of every part of the wall of the vestibule. In Lloyd’s account, 
too, of the foregut of Bathynomus, in which the discovery of some form 
of gastric mill was apparently expected, there is no clear evidence of the 
existence of such. 
In construction the foregut of Glyptonotus is fundamentally similar to 
that of Bathynomus , varying however in details, more especially in the 
posterior part. The involutions of the vestibular wall, to which Lloyd has 
given distinctive names, are all present, though their position is not so 
easily recognised from the external aspect. Thus the pair of “ anterior 
ampullae ” and the pair of “ posterior ampullae ” are readily seen in the 
interior. The two “ upper valvular processes ” take the form of a single 
medial chitinous plate, which may or may not be medially cleft at the 
posterior end. This plate is not an obvious duplicature of the wall like the 
other involutions, but a thin, stiffish sheet of ehitin, which reminds one of 
the capsule attached to the alar plate. Slightly concave interiorly, it 
is attached by its anterior edge to the roof of the vestibule, whence it 
projects freely backwards. The pair of “lower valvular processes” take 
the form of two long parallel tongue-shaped elevations of the vestibular 
floor, which extend to a much greater distance posteriorly than the free 
extremity of the overlying chitinous plate. 
The upper and the lower valvular processes are best seen from the 
posterior end, as when the cephalosome has been detached from the thorax 
— see fig. 22. The posterior free edge of the vestibule, which projects 
slightly into the midgut, does not lie exactly in the (vertical) plane of the 
cephalo-thoracic foramen, but slopes obliquely from above downwards and 
backwards. Surrounding this free edge on every side is a sinus formed by 
a forward pouching of the inidgut. 
We may now turn for a moment to consider the process of manducation 
and of swallowing. In manducation the gnathopodal hands (each one of 
which can be brought to lie under the mouth), the first maxillae and the 
mandibles would appear to be chiefly concerned. The gnathopods prob- 
ably act as packers, holding the food towards the mandibles and pushing 
it forwards between each bite. The lateral lobes of the first maxillae, 
working like many-pronged forks in the cleft between the paragnaths, 
probably help in keeping the food in the middle line. Repeated mandibular 
adductions alone are insufficient to cause any forward movement, as one 
can readily prove by trial on the dead animal with a wad of softened paper 
to represent food. 
The food having entered the pharynx, it would seem almost necessary 
