[ 177 1 
nal Surface of the outer Coat. The inner Membrane, 
being horny, gives Refiftance only ; wherefore the 
Stones are concave on that Side, andthefirft remark- 
able Scale (whereon all the others arc formed) may 
be perceiv’d in the Centre, the Brims or Circum- 
ferences of many of the reft being very appa- 
rent. At the time thefe Stones are not to be found 
in the Animal, there are little circular Spots, fome- 
what opake, and whiter than the reft of the Sto- 
mach, to be perceiv’d iii their Place ; nearly oppo- 
lite to which are tenacious mucilaginous Subftances, 
form’d like little Placentultf, and call’d by fome the 
Glands of the Brain : Thefe are larger, and more 
perceptible when the Stones are wanting ; but are 
not turned into Stones by different Degrees of In- 
duration, as fome have imagined them to be. 
It is believed, he fays, that they caft thefe Stones 
with their Shells, which they fhed every Spring 5 but 
he finds this is not the Way of getting rid of them ; 
for, a little before, or after the Time of their call- 
ing their Shell, the Stones break thro’ the internal 
or horny Coat of the Stomach, and being ground 
or broken by the three ferrated Teeth therein, be- 
come diffolv’d in the Space of a few Days, which 
makes it difficult to find them juft at this time, and 
thereby gives Ground to imagine they are caft with 
the Shells. He fays, however, he has found feveral 
of them in the Stomach partly confumed, one Spe- 
cimen whereof he has fent herewith, and a farther 
Proof that they are fo confumed, is, he thinks, their 
being never difeover’d in Rivers, tho’ the Fiffi rhem- 
felves be in great Plenty there ; and in the Shops it 
is obfervable, that many^ (of thefe ^Stones are of a 
brown 
