178 NATURAL HISTORY 



iracted, the concavity of the anterior extremity of the 

 shell may be seen : figure 283 shews it extended. 



421. Brachionus ^jZ/c«/«7z*\ The folded Brachionus 

 is shewn at figure 2/6 with the wheels fully extended; 

 and the two figures^ 2/8 and 279, give the upper part of 

 the same animalcule, with them both partially and en- 

 tirely contracted. The various parts, with the ova 

 attached to the body, may be readily distinguished in 

 figure 276. Found in sea water. 



422. Brachionus ovalis {Lepadella ovalis, E. — Myti- 

 lina lepidura, Bory.) The egg-shaped Brachionus. — This 

 creature has a very pellucid and strong shell in propor- 

 tion to its size, surpassing in strength that of the tortoise. 

 Its polytrochal organs and tail can be withdrawn into the 

 shell at pleasure. In figures 280 and 281, which are 

 amplified 380 times, may be observed the current it pro- 

 duces in the ambient water; the form of its golden- yellow 

 oesophagus, its stomach, and large alimentary canal, filled 

 with colouring matter, to distinguish it from the large ova 

 on each side. Length of body, about I -250th of an inch. 

 Found in running water among healthy confervae in 

 spring. 



423. Brachionus tripos. The three-spined Brachi- 

 onus is shewn, magnified, at figure 291. The shell is 

 composed of two pieces united by a suture along the 

 back, as in the B. mucronatus. The animalcule is 

 very diaphanous, shewing its bulbous oesophagus and 

 alimentary canal very distinctly, the latter of which is 

 often of a bright orange colour. The end of the shell is 



