ox 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 squillse 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 



