SECT. V. 



ROTIFERA. 



163 



name, are most characteristic in the common Eotifer 

 (fig. 137), where they consist of two disk-like lobes pro- 

 jecting from the body whose margins are fringed with 

 long cilia. It is the uninterrupted succession of strokes 

 given by these cilia, passing consecutively like waves 

 along the lobes, and apparently returning into them- 

 selves, which gives the impression of two wheels in 

 rapid rotation round their axes. 



The Brachionus pala (fig. 136) affords another instance 

 of the two- wheeled Kotifers. Though of unusually large 

 dimensions in its class, it is just visible to the naked 

 eye as a brilliant particle of diamond when moving in 

 a glass of water. Its transparent horny tunic, when 

 viewed in front with a micro- 

 scope, is a cup of elegant form, 

 bulging at the sides. One side 

 of the rim is furnished with 

 four spines, of which the middle 

 pair are slender and sharp as 

 needles, with a deep cleft between 

 them ; the other side of the rim 

 is undulated but not toothed, and 

 the bottom of the cup ends in 

 two broad blunt points. 



Between the terminal blunt 

 points there is a round opening 

 for the protrusion of the foot of 

 the animal. The tunic is of 

 glassy transparency, so that 

 every organ and function of the 

 animal can be traced with per- 

 fect distinctness. 



The foot of the animal is 

 long, rough and wrinkled, not 

 unlike the flexible trunk of an elephant. It can be 

 lengthened, shortened, drawn within, or pushed out of 



M 2 



Fig. 136. Brachionus pala, with 

 three eggs attached to its foot. 



