THE KOTIFEILE. 



173 



when once an unfortunate animalcule has been driven into its 

 gaping portals, it is presently crushed between a pair of formid- 

 able sharp-toothed jaws, which are constantly in motion, whether 

 the animal is taking food or not. The aliment, chewed .or 

 ground by this lively apparatus, passes into a slender canal or 

 tubular stomach, surrounded by a cushion-like mass of cells, 

 commonly coloured with the hue of the food, and therefore 

 concluded to be connected with the digestive system. 



The rotifera are either naked, or covered with a gelatinous 

 or horny sheath ; and many inhabit a tube formed by themselves, 

 attached by its lower end to some water- 

 plant, and open at the summit, from 

 which the animal protrudes when it 

 would exercise its active instincts, and 

 into which it retires for repose from 

 labour, or for refuge from alarm. The 

 majority, however, have a single or 

 furcated foot, which is often capable of 

 contraction by a set of telescopic sheath- 

 ings or false joints, and by means of 

 which they are enabled to secure a hold 

 of the minute stems of water-plants. 

 This is their ordinary position, when 

 keeping their wheels in action for a 

 supply of food or of water ; but they 

 have no difficulty in letting go their 

 hold, and either creeping along like 

 a leech, by alternate contractions and 

 extensions, or swimming away in search 

 of a new attachment. 



From the neck projects a telescopic 

 spur or tube (a), supposed to be an organ 

 of respiration ; and just below this are 

 seen two minute red specks, which are 

 the animal's eyes rudimentary indeed, 

 and probably endowed with no more of 

 visual power than a slight consciousness 

 of the stimulus of light. 



Some of the rotifera are inhabitants of salt water only, but by 

 far the larger proportion are found in collections of fresh water 



Philodina roseola. 

 a respiratory tube, b alimentary 

 canal, d terminal intestinal 

 pouch, e anal orifice. 



