ON CRUSTACEA. 
255 
little in front of and below its anterior extremity, and bristling 
with three or four small sharp and curved points. These two 
small teeth, according to the Baron, take hold of the food 
which comes from the mouth, and carry it between the two 
large teeth with flat crowns, which grind it between them and 
against the first plate which we have mentioned. Near the 
pylorus, a fleshy and oval projection is found behind the large 
teeth, in the interval which separates them ; and the pylorus 
itself is divided into two semi-canals by a middle ridge. The 
stomach has its peculiar muscles, and also extrinsic muscles, 
which are attached to the parts in the neighbourhood of the 
thorax, and which serve, with the first, to move the apparatus 
of five teeth that furnish the pylorus. 
When the astaci, or crawfish, are ready to moult, we find, 
applied within the stomach, and on each side, a calcareous, 
round, flatted, white stone, with concentric strata. These 
stones appear destined to furnish the matter, or a part of the 
calcareous matter, of the new testa ; for they diminish in size 
from the day after the moulting, and become totally dissolved 
in proportion as the new envelope acquires consistence. 
There is reason to believe that these bodies, which are vulgarly 
designated under the name of crabs' -eyes, and to which cer- 
tain imaginary properties have been attributed, are found in 
all the Crustacea properly so called, and especially in those 
which possess a very solid testa. 
In the squillie the stomach is small : its form is that of a 
triangular prism, membranaceous, and furnished on each side 
of its posterior extremity with a range of small pointed teeth. 
The onisci have the anterior part of their canal merely a little 
more bulky than the rest, and this increase of volume repre- 
sents the stomach. 
In Daphnia, the portion of the intestinal canal to which the 
name of stomach may be given, is in like manner merely larger 
than the rest of the tube. Its pylorus is not distinct, and the 
