Anatomy of Daphnia. 249 



forwards and inwards, and a prolongation or neck which is 

 somewhat hollowed out into a gutter (&), and articulates by 

 means of it with the "labre" or lip. These parts seem to be 

 almost constantly in motion, as if the animal were perpetually 

 employed in eating. J urine describes these organs some- 

 what differently from Straus, and his figures also vary a good 

 deal from those of this latter author. The "labre" or lip he 

 calls a sou-pape ;" and the jaws, though Straus denies his 

 having seen them at all, are, I suspect, what he calls " barbil- 

 lons," which he says consist of four rings, terminating in four 

 filaments. Their use is, he says, to push into the "sou-pape" 

 the bodies which ought to enter as aliment. The mouth, as I 

 have already stated, was placed by Swammerdam at the ex- 

 tremity of the beak, an opinion adopted also by Ledermuller. 

 Schaeffer, however, pointed out this error, and showed its real 

 situation, and DeGeer also pointed out its true place. Schaef- 

 fer describes the two mandibles, and fancied he also saw two 

 lips, but could not make them out distinctly, from the small- 

 ness of the shell. Part of the digestive canal is also situated 

 in the head, and part in the body. It commences immediately 

 behind the mouth in the form of an oesophagus, which is 

 short, narrow, slightly curved, and stretches obliquely for- 

 wards and upwards, and terminates immediately behind the 

 brain, in the stomach. 



The stomach is in form of a large vessel, diminishing slightly 

 in diameter from before, behind, and is curved somewhat in 

 the shape of an £ > or a figure 3 reversed, as described by Schaef- 

 fer. It runs almost all the length of the insect, opening by 

 the anus between the two first dentated arches of the poste- 

 rior part of the last segment of the body. Immediately be- 

 hind the eye, near the cardiac extremity of the stomach, we 

 see two vessels, curved upwards, the arch turned towards the 

 eye : these are described by Schaeffer, who considers them as 

 organs for furnishing the necessary juices for the nourish- 

 ment of the body. DeGeer says they resemble caeca. Jurine 

 supposes them to be organs proper for furnishing a juice 

 destined to perfect digestion. Straus at first considered them 

 as such also, but upon more mature examination at length 

 concluded them to be really caeca. The body of the animal. 



