26 
PEBBLE-SWALLOWING ANIMALS. 
Ten years afterwards^ the matter was brought before the Geological 
Society by Professor Seeley, the report of which is as follows : 
ON MAUISAURUS IN GAULT, AT FOLKESTONE. 
“ In the lower dorsal region of the animal about a peck of ovate and 
rounded pebbles occurred, of a diameter from quarter of an inch to 
nearly two inches. They are chiefly of opaque milky quartz, several 
are of black metamorphosed slate, and a few of fine-grained sandstone 
and hornstone, some of the pebbles showing a veined character, such as 
might be derived from the neighbouring Paloeozoic rocks of the North 
of France. Pebbles being of such rare occurrence in the Gault, it 
would seem natural to account for these associated stones on the 
hypothesis that they were swallowed by the animal with food, as is the 
case with certain living reptiles and birds. 
If this view should be held admissible, it would suggest that as the 
teeth were too small for anything but prehension, a structure analagous 
to a gizzard, or the stomach of an Edentate, may have used these 
pebbles to assist in breaking up or crushing the food on which the 
Saurians lived.” 
In the subsequent discussion, Mr. J. W. Hulke suggested “that the 
animal may not have swallowed the pebbles as an aid to the comminu- 
tion of food in its stomach, but that they were introduced in the 
stomachs of fish which it had swallowed. ^ The flesh and subsequently 
the bones of these would be digested and absorbed, whilst the indigest- 
ible stones, if the stomach of the Plesiosaurus was like that of 
Crocodiles, would be unable to pass through the small pyloric opening 
into the intestine, and must permanently remain in the stomach.” 
Ten years later (1887)^ we find a paper on this subject in our own 
Society’s Proceedings entitled, “ Remarks about Seals and their so 
called ‘Ballast Bag,’” by A. J. Harrison, M.B., Lon. This extremely 
interesting paper is too long to quote in full, and as it has been already 
printed in the Proceedings we must be contented with a summary of 
the main features. The writer (who has had a large and varied 
experience of the diseases and peculiarities of animals) first had his 
attention drawn to the subject by the discovery that a Seal, which had 
died in the Clifton Zoological Gardens, had a number of pebbles and 
other indigestible matter in the stomach. Further, on visiting a 
relative (the Rev. F. W. Bindley), he was shown what was called the 
“ Ballast Bag ” of a Seal (or Sea-lion), from the Cape of Good Hope, 
containing a large number of pebbles, and was informed that at the 
Cape fisheries the finding of such bags of pebbles was not at all unusual. 
Also, that about 1873 a small local commission was formed to investi- 
gate the matter, and several of these pebble bags were obtained; and 
brought home. Further, that conferring with Mf. Bland Sutton 
(pathologist to the London Zoological Society), it was stated that all 
Sea-lions examined there after death contained a varying amount of 
stones in their stomachs, and (an important feature) in all cases the 
^1877, Q.J.G.S., Vol. xxxiii., p. 546. 
2Bris. Nat. Proc., Vol. v., Partiii., 1887-8, p. 290. 
