7 98 Proceedings of Royal Society of Edinburgh. [sess. 
svineval, so that it may be assumed that the glands are at any rate 
not constant.* This, taken along with the width of the oesophagus, 
the peculiar expansions at its termination, and the absence of any 
but the most elementary masticatory apparatus, points to two facts 
— (a) that the food is swallowed immediately, and it is not in any 
way mixed with a salivary secretion ; ( b ) as there are no secreting 
glands in the oesophageal sacs, any digestive fluid that is mixed with 
the food in all probability regurgitates from the first true gastric 
compartment. In such case we should have to look upon the 
oesophageal sac as a “mixer” at all events, whatever may he its 
functions as a grinder ; and it might further be suggested that hard 
parts of crustaceans, and other indigestible matter, may be strained 
out in the diverticulum, and that they may then be ejected through 
the wide opening of the oesophagus. 
A somewhat similar process goes on in some of the carnivorous 
birds, e.g ., the owl, in which, however, the grinding and mixing 
apparatus is below or beyond the secreting portion of the gastric 
apparatus. We know that in birds, in which the gizzard with its 
strong muscular wall and horny epithelium is below the secreting 
area, the food is both ground and mixed with gastric juice, and it 
seems to be at least possible that the same process may go on in the 
dilated and strengthened portion of the oesophagus of the Narwhal, 
the gastric juice being from time to time driven back from the first 
true stomach. 
In connection with this question, we may refer~to Turner’s paper, 
in which he speaks of Tyson’s observations on the contents of the 
stomach (oesophageal pouch?) and oesophagus of the porpoise, as 
bones and other partially digested substances. Cleland also men- 
tions the presence of perfectly clean bones in the stomach of the 
white-beaked dolphin. One of us has on several occasions observed 
partially digested cuttle-fish in the mouth cavity of the recently 
killed Narwhal, so that the Narwhal has at least the power of 
vomiting its food under certain conditions, and it is also probable 
that indigestible material may be similarly ejected. 
* In the Greenland whale, Belcena mysticetus, near the extremity of the upper 
jaw, a blindly-ending depression is found on each side of the middle line 
within the cavity of the mouth, which, as Eschricht and Reinhardt suggest 
(“ Recent Memoirs on the Cetacea,” Memoirs of the Ray Society ), probably 
represent the rudiments of Stenson’s duct. 
