ROTIFERS. 



455 



of the wheels, it passes through a funnel as it were to the 

 inouth, which is situated rather lower down, and where 

 the food is crushed by teeth placed on the plates of the 

 jaw, with a hammer- like action ; from this point it passes 

 through the alimentary canal for the sustenance of the 

 animal. 



BRACHION^EA. Ehrenberg's genus Brachionus, " Spine- 

 bearing animalcules," belonging to the Rotiferce, are truly 

 interesting, from their very perfect and complex orga- 

 nisation. Some are entirely enclosed in a horny covering, 

 others only partially covered. Their structure, so beau- 

 tiful and symmetrical, has always made them favourites 

 with those who delight in microscopical studies. Bra- 

 chionus striatu*, "Striped shell animalcule" (No. 3, fig. 

 228), of an elegant, jug-like form, has the transparent 

 coat or carapace, striated and scalloped out at the upper 

 part ; through which the citron- 

 coloured inhabitant protrudes itself. 

 Two hornlike processes are appended 

 to its under-side. As occasions re- 

 quire, it sinks firmly and securely 

 within its crystal home, which is suffi- 

 ciently transparent to permit a view 

 of its organisation. Its progress is 

 effected by means of ciliary processes. 

 Brachionus Pala, or Anurce Cerm- 

 cornis, "Bent horn animalcule," is 

 possessed of double rotatory organs, 

 and four long processes, which project 

 above the external coat. It measures 

 the90thpart of an inch. Brachionus 

 Ovalis, " Egg-shaped brachionus," is 

 remarkable for the strength ^ of its 

 transparent coat, which is beyond 

 that of other horny creatures. Its 

 projecting tail, as well as head, is at 

 pleasure withdrawn into its very 

 strong case. Brachionus Dentatus, 

 " Toothed brachionus." This active, 

 bright pink-eyed little creature, the 90th part of an inch 

 iu size, is apparently enclosed in a two-valved shell, having 



Fig. 229. 

 Brachionus Ovalis, closed. 



